Agilent 86140B Series Measurement Applications User`s

Agilent 86140B Series Measurement Applications User`s
Agilent 86140B Series
Measurement Applications
User’s Guide
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86140-90088
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Second edition, February 2006
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Contents
1 Amplifier Test Application
Performing Measurements 1-4
ISS Test 1-16
TDE Test 1-29
Theory of Operation 1-49
Amplifier Test Application Remote Commands 1-55
ISS Measurement Method Example Program 1-66
TDE Measurement Method Example Program 1-69
2 Source Test Application
Performing Measurements 2-3
Characterizing DFB Lasers 2-9
Characterizing Fabry-Perot Lasers 2-16
Characterizing LEDs 2-24
Source Test Application Remote Commands 2-31
3 Passive Component Test Application
Performing Measurements 3-6
Designing Specification Sets 3-22
Passive Component Test Remote Commands 3-71
Sample Program 3-83
4 WDM Channel Analysis Application
Performing Measurements 4-5
WDM Channel Analysis Remote Commands 4-29
5 Customer Support
Agilent Technologies Service Offices 5-3
Cleaning Connections for Accurate Measurements 5-4
Contents-1
Contents
Contents-2
1
About the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
The Amplifier Test Application Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Starting the Amplifier Test Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Setting Up a Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Linear and Quadratic Interpolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
ISS Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
TDE Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Amplifier Test Application Remote Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Command Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
CALCulate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
CALibration Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
DISPlay Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
FORMat Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
INITiate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
INSTrument Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
TRIGger Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
ISS Measurement Method Example Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
TDE Measurement Method Example Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Amplifier Test Application
Amplifier Test Application
About the Application
About the Application
The Amplifier Test applications for the 86140-series optical spectrum analyzers
allow quick, accurate characterization of optical amplifiers with a minimum of
user inputs. All specifications and characteristics are derived from the 86140series specifications.
The applications measure the channel wavelengths, source power, gain, and
noise figure of an amplifier using Interpolation Source Subtraction (ISS) or
Time Domain Extinction (TDE) methods.
The ISS method is composed of one sweep to measure source signal
wavelength, power, and spontaneous emission, and a second set of sweeps to
measure the amplifier signal power and amplified spontaneous emission.
These measured parameters are used to calculate the gain and noise figure for
the amplifier. This method is suitable for all amplifier types.
The application calculates the following data and displays the results in the
display table:
•
•
•
•
•
•
•
•
Channel wavelength
Source Power
Gain
Noise figure
Source mean wavelength
Sum of source signal power
Amplifier mean wavelength
Sum of amplifier signal power
The Time Domain Extinction (TDE) method, available only on the 86146B,
measures the same parameters but uses time-domain extinction technique. It
requires that laser sources to be synchronously modulated. This method is
suitable only for amplifier types with slow time dynamics, for example, erbiumdoped devices.
1-2
Amplifier Test Application
About the Application
The Amplifier Test Application Menus
1-3
Amplifier Test Application
Performing Measurements
Performing Measurements
This section explains how to start and use the Amplifier Test applications. The
applications measure the channel wavelengths, source power, gain, and noise
figure of an amplifier using Interpolation Source Subtraction (ISS) and Time
Domain Extinction (TDE) methods.
Starting the Amplifier Test Application
1 Press the front-panel APPL’S key or, on the Applications menu, select Launch an
Installed Application.
The following screen is displayed:
1-4
Amplifier Test Application
Performing Measurements
Applications Panel and Menu
The panel and the menu change whenever an application is installed or uninstalled. Each installed application has an icon on the panel and a
corresponding softkey.
2 Press AMPLIFIER TEST to bring up a second menu with a choice of amplifier tests.
1-5
Amplifier Test Application
Performing Measurements
Amplifier Test Menu
3 Select either INTERPOLATION (ISS) TEST OR TIME DOMAIN EXTINCTION TEST (TDE).
Note: Time Domain Extinction Test is available only on the 86146B.
When the test is launched, the corresponding test menu is displayed.
1-6
Amplifier Test Application
Performing Measurements
Status Panel
The status panel is always visible at the top of the screen when the application
is running and consists of two lines of information. The top line contains the
current Device ID on the left and the current date and time on the right. The
second line contains a user-entered comment on the left and the measurement
status on the right. Note that Optimal Delay Search is available only in the TDE
measurement mode for the 86146B.
The above example indicates the application status is “ Idle”.
1-7
Amplifier Test Application
Performing Measurements
Setting Up a Measurement
The Measurement Setup dialog box allows you to define the parameters for the
measurement.
Amplifier Test Measurement Setup
The MEASUREMENT SETUP... softkey is enabled whenever the system is not
actively measuring. Selecting this key opens the Measurement Setup dialog
box.
1-8
Amplifier Test Application
Performing Measurements
Navigating the Measurement Setup Window
The softkeys allow you to navigate through the measurement setup dialog box.
The arrow softkeys allow you to navigate from field to field in the dialog box.
The highlighted parameter can be changed.
Select selects the highlighted parameter.
Defaults resets the parameters to their default condition.
Close Panel... saves the current setup and returns you to the previous menu.
The front-panel number keys, step keys, and knob on the OSA allow you to
enter a numeric value in the highlighted field.
1-9
Amplifier Test Application
Performing Measurements
Measurement setup parameters
Under manual operation, all measurement parameters are set to default by
pressing the DEFAULTS softkey. Otherwise, they retain the previous setting from
the last time the application was started. These settings are retained when
PRESET is pressed. Values are entered from the keypad or incremented using
the knob or step keys.
Start Wavelength
Default: 1530 nm
Sets the start wavelength for the measurement span. Units are fixed in nm.
Stop Wavelength
Default: 1570 nm
Sets the stop wavelength for the measurement span. Units are fixed in nm.
Wavelength Units
Default: nm
Selects the wavelength units, either nm or THz. These units are used in the
Display Table only.
Peak Excursion
Default: 10 dB
Sets the peak excursion value in dB. This is the amount of amplitude the trace
must rise and fall to be considered a peak. Lower values lead to more signals
being discerned, but if peak excursion is set too low, peaks in the noise floor
may be discerned as signals. If peak excursion is set too high, legitimate peaks
may not be discerned as signals.
Peak Threshold
Default: -55 dBm
1-10
Amplifier Test Application
Performing Measurements
Sets the peak threshold value in dBm. Power levels below this threshold are
not considered for peak search.
Interpolation Offset
Default: Auto
The offset can be entered manually, or calculated automatically. Auto mode,
uses (0.5×RBW+0.5nm)for the offset. Either Interpolation Method (that is,
Linear or Quadratic) can be used.
Interpolation Method
Default: Linear
Linear sets the noise marker ‘noise offset’ interval to the left and right of the
channel when making a noise power measurement. The noise power at the
channel wavelength is the interpolation value of the noise markers to the left
and right of the channel. The offset can be entered manually, or calculated
automatically using (0.5×RBW+0.5nm).
The system measures half the distance between channels and compares this
amount to the entered offset. If the half distance figure is closer to the channel,
the system will override the manually entered offset value with the half
distance value. This prevents adjacent channels from interfering with noise
measurements.
Quadratic uses four measured points. Two points are used on each side of the
channel to interpolate the noise floor at channel wavelength. The user
specifies the offset value for the two measured points closest to the channel
wavelength. The offsets for the outer two points are determined internally by
the application.
Resolution Bandwidth
Default: 0.2 nm
Sets the resolution bandwidth value to be used during peak sweep. This
determines the analyzer’s ability to display two closely spaced signals as two
distinct responses. Decreasing the resolution bandwidth provides a more
detailed sweep but increases the scan time.
1-11
Amplifier Test Application
Performing Measurements
The resolution bandwidth can be set to one of the following values:
• For 86140B Option 025, 86143B option 025, 86141B:
0.07 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86140B, 86142B, 86143B, 86145B:
0.06 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86144B, 86146B internal path:
0.06 nm, 0.07 nm, 0.1 nm, 0.14 nm, 0.2 nm, 0.33 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86144B, 86146B external path:
0.04 nm, 0.05 nm, 0.07 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
Video Bandwidth
Default: 100 Hz
Reduces noise and thus improves measurement repeatability. However, the
measurement time increases as the video bandwidth setting is decreased.
For the source and amplifier initial sweeps, the video bandwidth is fixed at
3 kHz. The default for source and amplifier noise and peak sweeps is 100 Hz.
The allowable input range is from 100 mHz to 3 kHz.
Trace Averaging
Default: Off
Improves measurement repeatability by smoothing out the noise. For
measurements involving slow polarization scrambling, trace averaging is
generally faster than video averaging.
When trace averaging is on, the initial default average count is 5. The allowable
input range is 1 to 1000 average counts.
ADC - Trigger Delay
Default: 10 ms.
Sets the trigger delay for the amplified spontaneous emission (ASE)
measurement for TDE. The sources are square-wave modulated. The trigger
delay should be set to 25% of the square-wave period plus 0.8 ms. The Optimal
Delay Search function will automatically calculate trigger delay.
1-12
Amplifier Test Application
Performing Measurements
Source Path Trace Offset
Default: 0.000 dB
Sets an offset to compensate for any losses caused by cables and connections
in the source path.
Amplifier Path Trace Offset
Default: 0.000 dB
Sets an offset to compensate for any losses caused by cables and connections
in the amplifier path.
Display Connection Prompts
Default: Yes
Displays equipment setup prompts when Measure Source or Measure
Amplifier are selected.
Include Shot Noise
Default: No
Sets a flag to include or exclude the 1/Gain term in noise figure calculations.
Continuous Amplifier Measurement
Default: Single
Allows you to select either single sweep measurement or continuous sweep
measurement mode.
1-13
Amplifier Test Application
Performing Measurements
Linear and Quadratic Interpolation
The setup panel and remote commands are provided for selecting the linear or
quadratic interpolation and the corresponding offset. For the linear method, the
offset is the distance of the two measured points from the channel wavelength.
For the quadratic method (four measurement points are used), the offset refers
to the two measured points closest to the channel wavelength. The offsets for
the outer two points are determined internally by the application.
To derive the value of amplified spontaneous emission (ASE) to calculate noise
figure, interpolation around each signal is used. Linear interpolation is best
when channel spacing is narrow. When channel spacing is wider, it is possible
to measure ASE at two points on either side of each signal (that is, quadratic
interpolation). The quadratic interpolation method will more accurately
estimate the ASE at the channel wavelengths in the gain region with high
curvature.
For narrow channel spacing, an inner point in the quadratic (four points) set
may become too close to an adjacent channel. The interpolation offset is
clipped to half the distance between the adjacent channels. When an outer
point in the 4-point set falls too close to an adjacent channel, the point is put
on the far side of the adjacent channel.
For the two boundary channels (at the low and high end of the span), any
shortage of data points on a boundary may cause the two points on the same
side of a boundary channel to become too close to each other. The program
automatically reverts to using a linear interpolation on a channel by channel
basis.
Linear sets the noise marker ‘noise offset’ interval to the left and right of the
channel when making a noise power measurement. The noise power at the
channel wavelength is the interpolation value of the noise markers to the left
and right of the channel. The offset can be entered manually, or calculated
automatically using (0.5×RBW+0.5nm).
The system measures half the distance between channels and compares this
amount to the entered offset. If the half distance figure is closer to the channel,
the system will override the manually entered offset value with the half
distance value. This prevents adjacent channels from interfering with noise
measurements.
1-14
Amplifier Test Application
Performing Measurements
Quadratic uses four measured points. Two points are used on each side of the
channel to interpolate the noise floor at channel wavelength. The user
specifies the offset value for the two measured points closest to the channel
wavelength. The offsets for the outer two points are determined internally by
the application.
1-15
Amplifier Test Application
ISS Test
ISS Test
There are two possible equipment configurations. Figure 1 uses a patchcord to
bypass the DUT for source calibraton while Figure 2 uses optical switches to
bypass the DUT.
Figure 1 Patch cord used to bypass the DUT
Figure 2 Optical Switches to bypass the DUT
1-16
Amplifier Test Application
ISS Test
Calibrating the Signal Path Offsets
To compensate for any losses caused by the cables and connections in the
signal paths, it is necessary to determine the path offsets using a power meter,
such as the 8163A lightwave multi-meter with an 81634A power sensor
module.
The objective of measuring and calculating the offsets is to transfer the
amplitude accuracy of the power meter to the application at it’s reference
plane.
Refer to “Measuring the Source” on page 22 and to “Measuring the Amplifier”
on page 1-24 for information on how to use the application to obtain source
and amplifier path wavelength and power values. These values are used in
calculating the path offsets.
To ensure accurate measurements, the system must be properly warmed up
and calibrated. All OSA specifications apply when the instrument’s internal
temperature has been stabilized after 1- hour of continuous operation, the auto
align routine has been run.
NOTE
As in all optical measurements, it is critical to follow good connector care practices.
Always clean the connector interfaces before connecting. Refer to “Cleaning
Connections for Accurate Measurements” in the optical spectrum analyzer user’s
guide.
CAUTION
Limit the power applied to the OSA to a maximum of +30 dBm total, +12 dBm
per channel. To avoid exceeding the total safe input power, an attenuator should
be installed at the OSA input. A 10 dB optical attenuator is available as option
030 for your OSA. Following this calibration procedure insures that this
attenuation value will be subtracted from the measurement.
To perform an Auto Align
Before entering the Amplifier Test application, connect a reference signal to
the instrument, then press AUTO ALIGN. This starts an automatic alignment
procedure that should be performed whenever the instrument has been moved,
subjected to large temperature changes, or warmed up at the start of each day.
1-17
Amplifier Test Application
ISS Test
To calculate offsets in a standard measurement setup
Figure 3 Reference Measurement
1 Connect the equipment as in Figure 3. Connect the source output and OSA input
fibers at the reference plane.
2 Measure the source path using the OSA Amplifier Test application Measure Source
function.
3 Without changing the setup, perform the Measure Amplifier function in the Amplifier
Test application. This step is necessary to have the source data appear in the Display
Table.
4 Record the source mean wavelength and sum of source signal power values from the
Display Table.
1-18
Amplifier Test Application
ISS Test
Figure 4 Power Meter Measurement
5 Connect the source to the power meter as in Figure 4. Set the power meter
wavelength parameter to the source mean wavelength value.
6 Measure the power and record the value.
7 Calculate the difference between the power meter reading and the application
reading using:
Offset = Power Meter Reading – Application Sum of Source Signal Power.
8 Enter the calculated value into the Measurement Setup dialog box as Source Path
Trace Offset and Amplifier Path Trace Offset. For a standard measurement setup, the
offsets in the source and amplifier paths will be the same.
9 To verify the offset is correct, repeat Measure Source and Measure Amplifier. The
source total power should read the same as measured by the power meter in Step 6.
The gain should be 0.0 dB for each channel.
10 After measuring and verifying the path offsets, you can connect the amplifier under
test as in Figure 1.
1-19
Amplifier Test Application
ISS Test
To calculate offsets in a measurement setup with optical switches
More complex measurement setups can provide an alternative path for
measuring the source. When this is the case, the offsets in the source and
amplifier paths will be different. This second procedure accounts for these
additional losses in a sample test configuration using switches.
Figure 5 Source Path Measurement
1 Connect the source output and receiver input fibers as shown in Figure 5.
2 Set switches to the source path (S) positions.
3 Measure the source path with the Measure Source function.
4 Without changing the setup, measure the source path with the Measure Amplifier
function.
5 From the Display Table, record the Source Mean Wavelength and Sum of Source
Signal Power.
6 Set the switches to the amplifier path (A) positions.
7 Measure the amplifier path with the Measure Amplifier function.
8 From the Display Table, record the Sum of Amplifier Signal Power.
9 Connect the power meter to the adapter at the reference plane as shown in Figure 5.
Set the power meter wavelength parameter to the source mean wavelength value.
1-20
Amplifier Test Application
ISS Test
10 Measure the power and record the value.
11 Calculate the difference between the power meter reading and the application
source reading using:
Offset = Power Meter Reading – Application Sum of Source Signal Power.
12 Enter the calculated value into the Measurement Setup dialog box as the Source
Path Trace Offset.
13 Calculate the difference between the power meter reading and the application
amplifier reading using:
Offset = Power Meter Reading – Application Sum of Amplifier Signal Power.
14 Enter the calculated value into the Measurement Setup dialog box as the Amplifier
Path Trace Offset.
15 To verify the offsets are correct, repeat Measure Source and Measure Amplifier. The
source and amplifier total power should read the same as measured by the power
meter in Step 10. The gain should be approximately
0.0 dB for each channel.
Figure 6 Amplifier Measurement
16 After measuring and verifying the path offsets, you can connect the amplifier under
test as in Figure 2.
1-21
Amplifier Test Application
ISS Test
Measuring the Source
After the offsets are calculated as described in the previous section, you can
proceed with the amplifier measurement. The first step of the two-step ISS
method is a set of sweeps that measure signal wavelength, power, and
spontaneous emission of the source. A second set of sweeps will measure the
amplifier signal power and amplified spontaneous emission.
The Measure Source step must be repeated if there is any change in the
measurement parameters or the source wavelength and power. Source data
will be lost when exiting the application and must be remeasured.
Measuring the Source
1-22
Amplifier Test Application
ISS Test
1 From the Interpolation ISS Test menu, select MEASURE SOURCE....
Note that the MEASURE AMPLIFIER... softkey is disabled until the source
measurement is completed.
Source Measurement Prompts
2 The system prompts you to connect the source to the OSA.
The display connection prompts can be turned off in the measurement setup
dialog box, in which case MEASURE SOURCE... will immediately initiate the
measurement.
3 Press CONTINUE to initiate the measurement.
MEASURE SOURCE... is replaced with STOP SOURCE MEASUREMENT... while the
measurement is in progress.
4 The progress of the measurement is noted on the status panel:
a An initial sweep is taken to set references, indicated by “Source Initial Sweep...”.
b A second sweep measures the peak of the signal, indicated by “Source Peak
Sweep...”.
1-23
Amplifier Test Application
ISS Test
c A third sweep measures the noise level, indicated by “Source Noise Sweep...”.
5 When the measurement is complete, the MEASURE AMPLIFIER... softkey is enabled. The
progress status label reads “Idle”.
Measuring the Amplifier
In the second step of the two-step process the amplifier is connected between
the source and the OSA. The system measures the peak and noise power for
the wavelengths measured in Measuring the Source and creates/updates the
Display Table.
1-24
Amplifier Test Application
ISS Test
Amplifier Measurement Prompts
1 Press M EASURE AMPLIFIER... to begin the process.
2 The system prompts you to install the device to be tested.
The display connection prompts can be turned off in the measurement setup
dialog box, in which case MEASURE AMPLIFIER... will immediately initiate the
measurement.
3 Press CONTINUE to initiate the measurement.
The MEASURE SOURCE... softkey is disabled. MEASURE AMPLIFIER... is replaced
with STOP AMP MEASUREMENT... while the measurement is in progress.
4 The progress of the measurement is noted on the status panel:
a An initial sweep is taken to set references, indicated by “Amplifier Initial
Sweep...”.
b A second sweep measures the peak of the signal, indicated by “Amplifier Peak
Sweep...”.
c A third sweep measures the noise level, indicated by “Amplifier Noise Sweep...”.
1-25
Amplifier Test Application
ISS Test
d After all the data is received, the application calculates the measurement results.
The progress label reads “Calculating Results...”.
5 When the measurement is complete, the progress status label reads “Idle”.
Amplifier Measurement Results
6 The measurement results will be displayed graphically. The points indicating the
amplifier gain and noise figure are displayed relative to the dB scale on the right side
of the graph.
1-26
Amplifier Test Application
ISS Test
NOTE
If Continuous Amplifier Measurement mode is selected in the measurement setup
dialog box, the measurement will continue to update the points on the display and in the
Display Table at the end of each measurement.
Viewing the Display Table
The DISPLAY TABLE... softkey is enabled when an amplifier measurement is
complete and valid data is available. The results are displayed in a table similar
to the one shown below. The Page Up and Page Down keys display previous
and next pages of data if available.
When in continuous sweep mode the Interpolation ISS Test application
continues to sweep and update the tabular data at the end of each
measurement.
1-27
Amplifier Test Application
ISS Test
At the end of the table, after all channels present have been measured, the
table will display values of source mean wavelength, sum of source signal
power, amplifier mean wavelength, and sum of amplifier signal power.
For a description of mathematical calculations refer to “Theory of Operation”
on page 49.
1-28
Amplifier Test Application
TDE Test
TDE Test
As with ISS, there are two possible equipment configurations as in Figure 1
and Figure 2. The main difference is the trigger signal from the synchronously
modulated source is required for the OSA. Figure 7 is the TDE setup for the
patchcord configuration for source measurement.
Figure 7 TDE setup for the patchcord configuration
Setting up the Source Modulation
To use TDE, it is necessary to setup synchronous source modulation on the
8166B lightwave multi-channel system and plug-in modules, or the 8164B
lightwave measurement system and plug-in modules. Any of the plug-in
modules including DFB lasers, tunable lasers, or compact tunables can be
configured for synchronous square-wave modulation. The internal modulation
source from one of the lasers is used to trigger all of the lasers from
synchronous modulation.
The modulation frequency may be from 20 kHz to 200 kHz. The 81662A and
81663A DFB modules may be modulated up to 100 kHz. A setting of 65 kHz is a
good initial setting for most erbium-doped fiber amplifiers.
1-29
Amplifier Test Application
TDE Test
For synchronized modulation of two or more laser modules in the same
mainframe, the setup is as follows:
1 Choose the “master” laser and set as follows:
a Menu > Modulation Source > Internal
b Menu > Modulation frequency > desired value
c Menu > Output trigger mode > Modulation
2 Set all “slave” modules:
a Menu > Modulation Source > Backplane (DFB modules require firmware version
4.0 or higher)
b Menu > Output trigger mode > disabled (important)
3 To pass the master trigger to the slaves, set up the mainframe through the Config
button under the screen:
Config > Trigger > Feedback (or Loopback)
Note: The master laser must always be turned on, if one or more slaves are on.
Otherwise, it causes an error due to the missing trigger.
If an additional mainframe is used, a BNC cable can connect its input trigger to
the master mainframe. Then this mainframe’s trigger configuration should be
left on default and all modules set to modulate on the backplane. A BNC cable
is required from the slave mainframe Input Trigger to the Output Trigger of the
Master mainframe. Finally, as indicated on Figure 7, a BNC cable is required
from the Source Trigger Out to the OSA ADC Trigger.
1-30
Amplifier Test Application
TDE Test
Calibrating the Signal Path Offsets
Refer to “Calibrating the Signal Path Offsets” on page 17.
Measuring the Source
After the offsets are calculated as described in the previous section, we can
proceed with the amplifier measurement. The first step of the two-step TDE
method is a set of sweeps that measure signal wavelength and power of the
source. A second set of sweeps will measure the amplifier signal power and
amplified spontaneous emission.
The Measure Source step must be repeated if there is any change in the
measurement parameters or the source wavelength and power. Source data
will be lost when exiting the application and must be remeasured.
Measuring the Source
1-31
Amplifier Test Application
TDE Test
1 From the TDE Test menu, select M EASURE SOURCE....
Note that the MEASURE AMPLIFIER... softkey is disabled until the source
measurement is completed.
Source Measurement Prompts
2 The system prompts you to connect the source to the OSA.
The display connection prompts can be turned off in the measurement setup
dialog box, in which case MEASURE SOURCE... will immediately initiate the
measurement.
3 Press CONTINUE to initiate the measurement.
MEASURE SOURCE... is replaced with STOP SOURCE MEASUREMENT... while the
measurement is in progress.
4 The progress of the measurement is noted on the status panel:
a An initial sweep is taken to set references, indicated by “Source Initial Sweep...”.
b A second sweep measures the peak of the signal, indicated by “Source Peak
Sweep...”.
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Amplifier Test Application
TDE Test
5 When the measurement is complete, the MEASURE AMPLIFIER... softkey is enabled. The
progress status label reads “Idle”.
Using the Optimal Delay Search
1 Connect the amplifier as shown in Figure 7.
2 Press Optimal Delay Search on the TDE application menu.
This routine will search for the optimal trigger delay for the source modulation
rate. The optimal delay sets the ASE measurement point to the midpoint of the
source Off period.
Occasionally, the Optimal Delay Search will not be able to find an optimal
setting. In this case, enter the trigger delay manually. The value should be 25%
of the modulation period plus 0.8 ms.
For a 65 kHz modulation rate, the period is 15.4 ms. The appropriate trigger
delay is 0.25 x 15.4 ms + 0.8 ms = 4.6 ms.
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Amplifier Test Application
TDE Test
Measuring the Amplifier
In the second step of the two-step process the amplifier is connected between
the source and the OSA. The system measures the peak and noise power for
the wavelengths measured in Measuring the Source and creates/updates the
Display Table.
Amplifier Measurement Prompts
1 Press M EASURE AMPLIFIER... to begin the process.
2 The system prompts you to connect the device to be tested.
The display connection prompts can be turned off in the measurement setup
dialog box, in which case MEASURE AMPLIFIER... will immediately initiate the
measurement.
3 Press CONTINUE to initiate the measurement.
The MEASURE SOURCE... softkey is disabled. MEASURE AMPLIFIER... is replaced
with STOP AMP MEASUREMENT... while the measurement is in progress.
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Amplifier Test Application
TDE Test
4 The progress of the measurement is noted on the status panel:
a An initial sweep is taken to set references, indicated by “Amplifier Initial
Sweep...”.
b A second sweep measures the peak of the signal, indicated by “Amplifier Peak
Sweep...”.
c A third sweep measures the noise level, indicated by “Amplifier Noise Sweep...”.
d After all the data is received, the application calculates the measurement results.
The progress label reads “Calculating Results...”.
5 When the measurement is complete, the progress status label reads “Idle”.
Amplifier Measurement Results
6 The measurement results will be displayed graphically. The points indicating the
amplifier gain and noise figure are displayed relative to the dB scale on the right side
of the graph. Negative noise figure values will not be displayed.
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Amplifier Test Application
TDE Test
NOTE
If Continuous Amplifier Measurement mode is selected in the measurement setup
dialog box, the measurement will continue to update the points on the display and in the
Display Table at the end of each measurement.
Viewing the Display Table
The DISPLAY TABLE... softkey is enabled when an amplifier measurement is
complete and valid data is available. The results are displayed in a table similar
to the one shown below. The Page Up and Page Down keys display previous
and next pages of data if available.
When in continuous sweep mode the TDE Test application continues to sweep
and update the tabular data at the end of each measurement.
At the end of the table, after all channels present have been measured, the
table will display values of source mean wavelength, sum of source signal
power, amplifier mean wavelength, and sum of amplifier signal power.
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Amplifier Test Application
TDE Test
For a description of mathematical calculations refer to “Theory of Operation”
on page 49.
Documenting the Results
There are two ways to document results in the Amplifier Test application. You
can either print them to a printer (specified under Printer Setup) or save them
to a floppy disk.
After the source and amplifier measurements are complete and valid
measurement data exists, the DOCUMENT RESULTS... softkey will be enabled.
Press DOCUMENT RESULTS... to display the Document Results selections.
Document Results Menu
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Amplifier Test Application
TDE Test
Saving the results to a floppy disk
Press the SAVE RESULTS TO FLOPPY softkey to save the current results to a file on
the floppy drive.
If a device ID has been entered, the name of the file is defaulted to the last 8
characters of the device ID.
If no ID exists, a message prompts you to “Enter a Device ID as Filename”. Press
CLOSE PANEL... to return to the Document Results menu and select ENTER ID... .
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Amplifier Test Application
TDE Test
If the ID already exists, the warning “Overwrite File?” is displayed. Press
OVERWRITE FILE to overwrite the existing file or CANCEL to return to the Enter ID
screen.
A successful save operation is confirmed by a progress message displayed on
the bottom left of the OSA display.
The current file is saved in ASCII (.csv) spreadsheet format. Graphics data is
stored in Computer Graphics Metafile (.cgm) graphics format. This is a vector
graphics format that describes pictures and graphical elements in geometric
terms.
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Amplifier Test Application
TDE Test
Using the alphanumeric panel
Alphanumeric panels, such as the Device ID panel, allow you to enter
identification and comment labels for the devices you test.
An example of an alphanumeric panel
1-40
Amplifier Test Application
TDE Test
Select selects the highlighted character.
The arrow softkeys allow you to navigate from character to character in the
dialog box.
Backspace removes a previously selected character.
Continue saves the current entry and returns you to the previous menu.
1-41
Amplifier Test Application
TDE Test
To enter a device ID
Press ENTER ID... to access the Device Identification panel. Use the arrow and
Select softkeys to enter the device ID. A maximum of 20 characters can be
entered in this field.
Device Identification panel
To enter comments
Press ENTER COMMENTS... to access the Enter Comments panel. Use the arrow
and Select softkeys to enter a comment. A maximum of 50 characters can be
entered in this field.
Enter Comments panel
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Amplifier Test Application
TDE Test
Printing the results
1 Press PRINT R ESULTS to print the results to the target printer.
The default setting is the internal printer and the default printout type is table
only.
2 Press PRINTER SETUP... to access the Printer Setup dialog box.
3 Use the arrow and Select softkeys to select the target printer, and the printout type.
This setting is reset when the front-panel PRESET key is pressed, otherwise the
previous setting from the last time the application was started is retained.
Printer Setup panel
The print operation is confirmed by a progress message displayed on the
bottom left of the OSA display.
4 CLOSE PANEL... returns to the Document Results Menu.
The four possible print formats are shown in the following four figures:
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Amplifier Test Application
TDE Test
Graphics and Table, Internal Printer
1-44
Amplifier Test Application
TDE Test
Graphics and Table, External Printer
1-45
Amplifier Test Application
TDE Test
Table Only, Internal Printer
1-46
Amplifier Test Application
TDE Test
Table Only, External Printer
1-47
Amplifier Test Application
TDE Test
Viewing Errors
Error Menu
Any errors generated in the course of the test or result documentation will
generate error codes. These codes can be accessed by pressing the VIEW
ERRORS... softkey. If any errors exist, the appropriate selection on the error
menu will be enabled.
1-48
Amplifier Test Application
Theory of Operation
Theory of Operation
Interpolation Source Subtraction
The Amplifier Test application uses the Interpolation Source Subtraction (ISS)
measurement technique to determine the noise figure of an amplifier. This
method determines the amplified spontaneous emission (ASE) of the amplifier
at the signal wavelength by measuring the noise power levels at wavelengths
just above and below the signal and then interpolating to determine the noise
level at the signal wavelength.
First, the spontaneous emission of the source is determined by measuring it’s
level at a specified offset (typically 1nm) above and below the signal
wavelength and then taking the average of the measurements. This offset can
be specified in the Measurement Setup dialog box, or calculated automatically
using (0.5×RBW+0.5nm).
The same procedure is then used to determine the spontaneous emission at
the output of the amplifier. The ASE and noise figure of the amplifier can then
be determined using its calculated gain and these two spontaneous emission
values.
Gain and Spontaneous Emission
The purpose of an amplifier is to provide gain, which is defined as the ratio of
output signal power to input signal power. These measured powers are
actually the sum of the signal power and the small amount of spontaneous
emission at the signal wavelength. This additional measured power can be a
factor when high spontaneous emission levels are present.
1-49
Amplifier Test Application
Theory of Operation
Amplified Spontaneous Emission (ASE)
Ideally, an amplifier would amplify the input signal by it’s gain and produce no
additional output. However, amplifiers also produce ASE, which adds to the
spontaneous emission of the source. This ASE is calculated as the difference
between the output spontaneous emission power and the equivalent source
spontaneous emission power measured at the amplifier output.
Interpolating Noise
In order to correctly determine the noise figure, the ASE level must be
determined at the signal wavelength. This cannot be directly measured
because the ASE is masked by the signal power level. The ISS method uses
filter characteristics of the OSA to reject the signal and measure the
spontaneous emission levels at wavelengths near each signal.
To determine the noise level at the signal wavelength, several measurement
sweeps are taken. The initial sweep adjusts the reference level to peak. The
second sweep measures the power level and channel wavelength for each
channel present, as well as the maximum noise value. The third and final
sweep sets the reference level to the maximum noise level measured in the
second sweep. It then measures the noise power for each channel by taking
measurements above and below the channel wavelength at the predetermined
offset value. These values are interpolated to determine the noise value at the
channel wavelength. The linear interpolation method takes two
measurements, one on each side of the channel. The noise at the channel
wavelength is interpolated based on these two measurements.
The quadratic interpolation method takes four measurements, two on each
side of the channel. This method approximates the curvature to account for
curvature of the noise spectrum profile. In the vicinity of each channel, the
noise generally assumes a Gaussian profile which can be modeled as a
quadratic curve in dB. The noise at the channel wavelength is estimated based
on the four measurements.
1-50
Amplifier Test Application
Theory of Operation
The noise figure of the amplifier is calculated from the measurements of the
signal and ASE power levels using the following equations:
P out – N out
Gain = -------------------------P in – N in
Gain ( dB ) = 10 log ( Gain )
N out – ( N in G ) 1
NoiseFactor
----------------------------------- --hvB w G
G
NoiseFigure = 10 log ( NoiseFactor )
Where:
•
•
•
•
•
•
•
•
•
Pout = amplifier output power
Pin = amplifier input power
Nout = interpolated output noise power
Nin = interpolated source noise power
G = amplifier gain
1/G = the optional shot noise component
Bw = optical spectrum analyzer’s noise bandwidth in Hertz
h = Plank’s constant (6.626 × 10-34 Watt seconds2)
v = signal frequency in Hertz
1-51
Amplifier Test Application
Theory of Operation
Time Domain Extinction Technique
Erbium-Doped Fiber Recovery from Saturation
The core of an optical amplifier, for wavelengths around 1550 nm, is a singlemode fiber doped with erbium. The erbium ions are shifted to higher energy
levels by some pump lasers. The activated electrons remain in a meta stable
level for some time. Without any signal at the amplifiers input, these electrons
eventually fall down and emit some light randomly. However, if an input signal
is applied, then the incoming wave stimulates the electrons to fall down and
thus emit their energy coherently with the incoming wave. This is the main
effect of the optical amplification. The amplification applies to randomly
emitted photons as well, so the output spectrum of an optical amplifier
consists of an amplified input spectrum (if applied) and the amplified
spontaneous emission (ASE, which represents the noise from the amplifier.)
The more electrons used for stimulated emission, the fewer remain for random
emission (and vice versa). Without an input signal, the ASE is much higher
than with an input signal. Therefore, the ASE has to be measured when the
amplifier is driven into saturation by an input signal.
The time domain extinction technique (TDE) takes advantage of the fact that
the meta stable energy level of the erbium ion has a time constant of several
hundreds of microseconds. Immediately after the input signal is turned off, the
ASE power remains at the same level it was in the presence of the input signal.
Then it starts to rise in an exponential fashion until it reaches the level of an
undriven condition.
1-52
Amplifier Test Application
Theory of Operation
Figure 8 ASE time domain characteristics
The time characteristics can be tested using a laser source being modulated at
a low frequency. Before the falling edge of the modulated laser, the amplifier
noise (ASE) has stabilized at a saturated level. This power is the sum of the
amplified input signal and the ASE which is very small due to the saturation of
the amplifier. Immediately after the falling edge, the output signal consists of
only ASE from the amplifier; that is, it does not contain the amplified signal any
more, nor has it any sidemodes or spontaneous emission from the source. This
fact allows accurate characterization of the ASE even at the wavelength of the
saturating signal.
1-53
Amplifier Test Application
Theory of Operation
Because the power after the edge is up to a thousand times smaller than the
power before, the measurement equipment must recover from the large signal
in a very short time. The next figure shows typical recovery performance of the
Agilent 8614XB family of optical spectrum analyzers. Within ten microseconds
after the large signal has disappeared, the OSA can measure a 30 dB weaker
signal with an accuracy of better than ±0.2 dB.
Figure 9 OSA recovery performance
1-54
Amplifier Test Application
Amplifier Test Application Remote Commands
Amplifier Test Application Remote Commands
The Agilent 86140B Series Optical Spectrum Analyzer Programming Guide for
the mainframe provides detailed information on remote programming of the
instrument. Only commands unique to the Amplifier Test application are
included in this section.
The Amplifier Test application remote command set is comprised of two types
of commands:
General Application support commands
These are part of the base firmware and support applications in general. They
allow you to get a list of installed applications, load/unload an application, and
so on. These commands are grouped under:
• INSTrument Subsystem Commands
Amplifier Test application specific commands
These remote commands are specific to the Amplifier Test application and
allow you to control the application remotely. They are grouped under the
following subsystems:
• CALCulate Subsystem Commands
• FORMat Subsystem Commands
• INITiate Subsystem Commands
• SENSe Subsystem Commands
For more information, refer to the Remote Operation section in the Agilent
86140B Series Optical Spectrum Analyzer Programming Guide, or to the
following book:
SCPI Consortium. SCPI–Standard Commands for Programming Instruments, 1997
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Amplifier Test Application
Amplifier Test Application Remote Commands
Command Conventions
Table 1
Convention
Description
<>
Angle brackets indicate text strings entered by the developer.
[]
Square brackets indicate that the keyword DEFAULT can be used instead
of a value or a variable for that parameter. Refer to the actual command
description for the behavior when the DEFAULT keyword is used for a
parameter.
|
Indicates a choice of one element from a list.
{}
Braces indicate a group of constants to select from. Each constant is
separated by the | character.
name
Indicates the variable for which you provide a descriptive name. Any letter
(Aa-Zz) followed by letters, digits (0-9) and underscore (_). Only the first 32
characters are significant.
spec_min
–infinity. The parameter spec_min cannot be a variable, only a constant or
DEFAULT.
spec_max
+infinity. The parameter spec_max cannot be a variable, only a constant or
DEFAULT.
from
Start wavelength or frequency of trace in nm (default) or THz.
to
Stop wavelength or frequency of trace in nm (default) or THz.
excursion
+excursion: means excursion dBs up (for example, from a pit).
-excursion: means excursion dBs down (for example, from a peak).
ref_pt
The reference point to be used for a measurement keyword.
CALCulate Subsystem Commands
The CALCulate subsystem performs post-acquisition data processing. The
CALCulate subsystem operates on data acquired by a SENSe function.
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Amplifier Test Application
Amplifier Test Application Remote Commands
CALCulate:DATA:CPOWers?
Downloads the array of source channel powers measured. The data is returned
in either an ASCII or binary form as determined by the FORMat:DATA
command. The number of data points in this array is determined by the
CALCulate:DATA:NCHannels? query.
CALCulate:DATA:CGAin?
Downloads the array of channel gain values measured. The data is returned in
either an ASCII or binary form as determined by the FORMat:DATA command.
The number of data points in this array is determined by the
CALCulate:DATA:NCHannels? query.
CALCulate:DATA:CNF?
Downloads the array of channel noise figure values measured. The data is
returned in either an ASCII or binary form as determined by the FORMat:DATA
command. The number of data points in this array is determined by the
CALCulate:DATA:NCHannels? query.
CALCulate:DATA:CSTats?
Downloads the following statistics using a single query:
•
•
•
•
Source mean wavelength
Sum of source signal power
Amplifier mean wavelength
Sum of amplifier signal power
The data is returned in either an ASCII or binary form as determined by the
FORMAT:DATA command.
CALCulate:DATA:CWAVelengths?
Downloads the array of channel wavelengths measured. The data is returned in
either an ASCII or binary form as determined by the FORMat:DATA command.
The number of data points in this array is determined by the
1-57
Amplifier Test Application
Amplifier Test Application Remote Commands
CALCulate:DATA:NCHannels? query. The units are either nanometers or
terahertz and can be changed using the CALCulate:DATA:TABLe:WAVe
command.
CALCulate:DATA:NCHannels?
Queries the number of channels detected in the last measurement. The data is
returned as an ASCII integer.
CALCulate:DATA:TABLe:WAVe NM|THZ
CALCulate:DATA:TABLe:WAVe?
Sets the wavelength units used for the tabular display and for the
CALCulate:DATA:CWAVelengths remote query. Default units are NM.
The instrument x-axis display always displays wavelength in nanometers and is
not affected by this command.
Example
CALC:DATA:TABL:WAV NM
! Assign table units to nm
CALCulate:OFFSet:AMPLifier <numeric_value>
CALCulate:OFFSet:AMPLifier?
Sets the trace level offset or power correction factor in dB for the amplifier
path. The “dB” terminator is not required in the command.
Example
CALC:OFFS:AMPL 11
CALC:OFFS:AMPL?
1-58
! Assign an amp offset
! Read offset
Amplifier Test Application
Amplifier Test Application Remote Commands
CALCulate:OFFSet:SOURce <numeric value>
CALCulate:OFFSet:SOURce?
Sets the trace level offset or power correction factor in dB for the source path.
The “dB” terminator is not required in the command.
Example
CALC:OFFS:SOUR 13
CALC:OFFS:SOUR?
! Assign a source offset
! Read offset
CALCulate:PEXCursion[:PEAK] <numeric_value>
CALCulate:PEXCursion[:PEAK]?
Sets the peak excursion value for the marker search routines. The peak
excursion value is used to determine whether or not a local maximum in the
trace is to be considered a peak. To qualify as a peak, both sides of the local
maximum must fall by at least the peak excursion value.
Example
CALC:PEX 5
CALC:PEX?
! Assign peak excursion
! Read peak excursion
CALCulate:THReshold <numeric_value> [DBM]
CALCulate:THReshold?
Specifies the value for the peak search threshold. Peaks with amplitudes below
this value will not be included in the channel count.
Units are DBM.
Example
CALC:THR -40 DBM
CALC:THR?
! Assign a peak threshold
! Read peak threshold
CALCulate:SNOise [ON|OFF|0|1]
CALCulate:SNOise?
Sets the shot noise term included/excluded in noise figure calculations.
Default value is false. By default the shot noise term will not be added to the
noise figure.
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Amplifier Test Application
Amplifier Test Application Remote Commands
Example
CALC:SNO OFF
CALC:SNO?
! Turn off shot noise term
! Read shot noise
CALibration Subsystem Commands
This subsystem has the function of performing system calibration.
CALibration Alignment
Performs an automatic alignment of the instrument at the wavelength of the
largest signal found in full span. This aligns the monochromator output with
the photodetector for improved amplitude accuracy.
Syntax
CAL:ALIG
Related Key
Auto Align
DISPlay Subsystem Commands
The DISPlay subsystem controls the selection and presentation of textual,
graphical, and TRACe information.
DISPlay[:WINDow]:DUT:COMMent<string>
Enters a new comment string for the device under test.
DISPlay[:WINDow]:DUT:COMMent?
Returns the comment string for the device under test.
DISPlay[:WINDow]:DUT[:ID]<string>
Enters a new identification string for the device under test.
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Amplifier Test Application
Amplifier Test Application Remote Commands
DISPlay[:WINDow]:DUT[:ID]?
Returns the identification string for the device under test.
FORMat Subsystem Commands
The FORMat subsystem sets a data format for transferring numeric and array
information.
FORMat[:DATA] REAL[32,64]|ASCII
FORMat[:DATA]?
Specifies the format used during data transfer via GPIB. This command affects
data transfers for the CALCulate[:DATA] subsystem.
The ASCII format is a comma-separated list of numbers.
The REAL format is a definite-length block of either 32-bit or 64-bit floatingpoint binary numbers. The definite-length block is defined by IEEE 488.2: a "#"
character, followed by one digit (in ASCII) specifying the number of length
bytes to follow, followed by the length (in ASCII), followed by length bytes of
binary data. The binary data is a sequence of 8-byte floating point numbers,
default to 64-bit and selectable to 32-bit.
INITiate Subsystem Commands
The INITiate subsystem is used to control the initiation of the TRIGger
subsystem.
INITiate:IMMediate[:SEQuence [1|2]]
Initiates the source measurement (sequence 1) or amplifier measurement
(sequence 2) based on the sequence number. Default is sequence 2.
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Amplifier Test Application
Amplifier Test Application Remote Commands
INSTrument Subsystem Commands
The INSTrument subsystem provides a mechanism to identify and select
logical instruments by either name or number. Arguments and responses are
case sensitive.
INSTrument:CATalog?
{Filter1,PowerMeter, OSA,PassiveComponent,WDM_AutoScan,Amp_ISS_Test, Amp_TDE_Test,<null>}
Comma-separated list of strings representing the modes and applications
supported in the instrument.
INSTrument:CATalog:FULL?
{OSA,0,Filter1,1,PowerMeter,2,PassiveComponent,3,WDM_AutoScan,4,Amp_ISS_Test,5,
Amp_TDE_Test,6}
Comma-separated list of string-numeric pairs representing the modes and
applications supported in the instrument.
INSTrument:SELect <identifier> identifier - string
INSTrument:NSELect <numeric_value>
INSTrument:NSELect?
Loads the application or instrument mode specified. Use the CATalog:FULL?
command to obtain the number. Firmware revisions will add additional
applications and the order may vary.
Example
INST:SEL ‘Amp_ISS_Test’
INST:NSEL5
INST:SEL?
INST:SEL ‘Amp_TDE_Test’
INST:NSEL6
INST:SEL?
1-62
!Select amplifier interpolated source
subtraction test
!Select amplifier test by number
!Read ‘Amp_ISS_Test’
!Select amplifier time domain extinction
test
!Select amplifier test by number
!Read ‘Amp_TDE_Test’
Amplifier Test Application
Amplifier Test Application Remote Commands
SENSe Subsystem Commands
The SENSe setup commands control the specific settings of the device.
SENSe:AVERage:COUNt <integer>
SENSe:AVERage:COUNt?
Sets and queries the number of sweeps that will be averaged. Range is 1-1000.
Command will also turn on trace averaging if it is not already on.
Example
SENS:AVER:COUN <INT>
SENS:AVER:COUN?
! Sets count for trace averaging
! Gets count for trace averaging
SENSe:AVERage:[STATe] <ON|OFF|1|0>
SENSe:AVERage:[STATe]?
Turns trace averaging on or off and queries trace averaging state.
Example
SENS:AVER[:STAT] <on|off.>
SENS:AVER[:STAT]
! Turns trace averaging on/off
! Gets trace averaging on/off
SENSe:BANDwidth|BWIDth[:RESolution]: <numeric_value> [M|NM|UM|A]
SENSe:BANDwidth|BWIDth[:RESolution]?
Sets the resolution bandwidth value to be used. Resolution bandwidth
determines the instrument’s ability to display two closely spaced signals as
two distinct responses.
The resolution bandwidth can be set to one of the following values:
• For 86140B Option 025, 86143B option 025, 86141B:
0.07 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86140B, 86142B, 86143B, 86145B:
0.06 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86144B, 86146B internal path:
0.06 nm, 0.07 nm, 0.1 nm, 0.14 nm, 0.2 nm, 0.33 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
• For 86144B, 86146B external path:
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Amplifier Test Application
Amplifier Test Application Remote Commands
0.04 nm, 0.05 nm, 0.07 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm.
For the greatest measurement range and signal to noise ratio performance, a
resolution bandwidth of 10 nm is recommended. Narrower bandwidths can be
used if greater wavelength resolution is required.
Example
SENS:BWID .5 NM
SENS:BWID?
! Select a RBW for measurement
! Read bandwidth
SENSe:BANDwidth|BWIDth: VIDeo <real>
SENSe:BANDwidth|BWIDth:VIDeo?
Permits setting video bandwidth via remote interface with the SCPI command.
Example
SENS:BAND:VID <param>
SENS:BAND |BWID:VID ?
! Sets video bandwidth
! Gets video bandwidth
SENSe:INTerpolation:METHod <LINear|QUADratic>
SENSe:INTerpolation:METHod?
Allows selection and query of the interpolation method (linear or quadratic).
Example
SENS:INT:METH <LIN|QUAD>
pt
SENS:INT:METH?
method
! Sets interpolation method, linear or 4
quad
! Gets current interpolation
SENSe:INTerpolation:OFFSet:VALue?
SENSe:INTerpolation:OFFSet:AUTO [ON|OFF|0|1]
SENSe:INTerpolation:OFFSet:AUTO?
Specifies the noise measurement locations for interpolation. If auto is set to
true, then the application will calculate the best offset value. Default units are
NM.
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Amplifier Test Application
Amplifier Test Application Remote Commands
SENSe:[WAVelength:]STARt <numeric_value> [M|NM|UM|A|HZ|KHZ|MHZ|GHZ]
SENSe:[WAVelength:]STARt?
Specifies the start wavelength for the Amplifier Test Application. Default units
are NM.
Example
SENS:STAR 1500 NM
SENS:STAR?
! Select the start wavelength
! Read wavelength
SENSe:[WAVelength:]STOP <numeric_value> [M|NM|UM|A|HZ|KHZ|MHZ|GHZ]
SENSe:[WAVelength:]STOP?
Specifies the stop wavelength for the Amplifier Test application. Default units
are NM.
Example
SENS:STOP 1540 NM
SENS:STOP?
! Select the stop wavelength
! Read wavelength
TRIGger Subsystem Commands
TRIGger[:SEQuence]:DELay:AUTO
For 86146B only
Initiates a routine to automatically find the optimum trigger delay. TDE uses the
source external trigger output to trigger the OSA to sample when the source is
off. The OSA will measure the ASE associated with the amplifier.
TRIGger[:SEQuence]:DELay<time>
TRIGger[:SEQuence]:DELay?
For 86146B only
Sets the trigger delay used for the TDE measurement. TDE uses the source
external trigger output to trigger the OSA to sample when the source is off. The
OSA will measure the ASE associated with the amplifier.
1-65
Amplifier Test Application
ISS Measurement Method Example Program
ISS Measurement Method Example Program
Program
10 !***************************** Select Amplifier ISS Test *****************************
20 !
30 ASSIGN @Osa TO 723;EOL CHR$(10) END
! Use LF and EOI as command
terminators
40 !
50 OUTPUT @Osa;"inst:sel 'Amp_ISS_Test'"
! Select Amp ISS test
60 !
70 !***************************** Measurement Setup **********************************
80 !
90 OUTPUT @Osa;"sens:int:meth quad"
! Select 4 pt quad int
100 !
110 !***************************** Measure the Source *********************************
120 !
130 INPUT "Connect source and press Enter to continue",A$
140 OUTPUT @Osa;"init:imm:seq 1"
! Take a source measurement
150 !
160 !***************************** Measure the Amplifier *******************************
170 !
180 INPUT "Connect amplifier and press Enter to continue",A$
190 OUTPUT @Osa;"init:imm:seq 2"
! Take an amplifier measurement
200 !
210 !***************************** Read the Results ************************************
220 !
230 OUTPUT @Osa;"calc:data:nch?"
! Find number of channels measured
240 ENTER @Osa;Nchannels
250 PRINT "Number of channels"
260 PRINT Nchannels
270 PRINT
280 !
290 ALLOCATE Datarray(1:Nchannels)
300 !
310 OUTPUT @Osa;"calc:data:cwav?"
! Read in the channel wavelengths
320 ENTER @Osa;Datarray(*)
330 PRINT "Channel wavelengths"
340 PRINT Datarray(*)
350 PRINT
360 !
370 OUTPUT @Osa;"calc:data:cpow?"
! Read in the channel powers
380 ENTER @Osa;Datarray(*)
390 PRINT "Channel powers"
400 PRINT Datarray(*)
410 PRINT
420 !
430 OUTPUT @Osa;"calc:data:cga?"
! Read in the channel gains
440 ENTER @Osa;Datarray(*)
1-66
Amplifier Test Application
ISS Measurement Method Example Program
450 PRINT "Channel gains"
460 PRINT Datarray(*)
470 PRINT
480 !
490 OUTPUT @Osa;"calc:data:cnf?"
! Read in the channel noise figures
500 ENTER @Osa;Datarray(*)
510 PRINT "Channel noise figures"
520 PRINT Datarray(*)
530 PRINT
540 !
550 !***************************** Read the Test Results ********************************
560 !
570 OUTPUT @Osa;"calc:data:cst?"
! Query statistics table Results
580 ENTER @Osa;Sourmwl;Sumsrcpwr;Ampmwl;Sumsamppwr
590 PRINT "Source Mean WL"
600 PRINT Sourmwl
610 PRINT
620 !
630 PRINT "Sum of Src Sig Pwr"
640 PRINT Sumsrcpwr
650 PRINT
660 !
670 PRINT "Amplifier Mean WL"
680 PRINT Ampmwl
690 PRINT
700 !
710 PRINT "Sum of Amp Sig Pwr"
720 PRINT Sumsamppwr
730 PRINT
740 !
750 !***************************** Exit the Application *********************************
760 !
770 OUTPUT @Osa;"*RST"
! Exit amplifier ISS application
780 LOCAL @Osa
790 END
===========================================================
Number of channels
+3
Channel wavelengths
+1.55385770E-006,+1.55485825E-006,+1.55594775E-006
Channel powers
-3.14317435E+000,-5.22143262E+000,-2.93054801E+000
Channel gains
+7.97910584E-003,-2.28063112E-003,-8.10500742E-003
Channel noise figures
+9.91000000E+037,+9.91000000E+037,+9.91000000E+037
Source Mean WL
+1.55492086E-006
1-67
Amplifier Test Application
ISS Measurement Method Example Program
Sum of Src Sig Pwr
1.12172171E+000
Amplifier Mean WL
+1.55491862E-006
Sum of Amp Sig Pwr
+1.12099868E+000
1-68
Amplifier Test Application
TDE Measurement Method Example Program
TDE Measurement Method Example Program
Program
10 !*****************************Select Amplifier TDE Test ******************************
20 !
30 ASSIGN @Osa TO 723;EOL CHR$(10) END
! Use LF and EOI as command
terminators
40 !
50 OUTPUT @Osa;"inst:sel 'Amp_TDE_Test'"
! Select Amp TDE test
60 !
70 !*****************************Measurement Setup **********************************
80 !
90 !
100 OUTPUT @Osa;"sens:int:meth quad"
! Select 4 pt quad int
110 !
120 !***************************** Measure the Source ********************************
130 !
140 INPUT "Connect source and press Enter to continue",A$
150 OUTPUT @Osa;"init:imm:seq 1"
! Take a source measurement
160 OUTPUT @Osa;"trig:seq:del:auto"
! Determine trigger delay
170 !
180 !***** Measure the Amplifier *****************************************************
190 !
200 INPUT "Connect amplifier and press Enter to continue",A$
210 OUTPUT @Osa;"init:imm:seq 2"
! Take an amplifier measurement
220 !
230 !*****************************Read the Results ***********************************
240 !
250 OUTPUT @Osa;"trig:seq:del?"
! Find trigger delay
260 ENTER @Osa;Trigdelay
270 PRINT "Trigger delay"
280 PRINT Trigdelay
290 PRINT
300 !
310 OUTPUT @Osa;"calc:data:nch?"
! Find number of channels measured
320 ENTER @Osa;Nchannels
330 PRINT "Number of channels"
340 PRINT Nchannels
350 PRINT
360 !
370 ALLOCATE Datarray(1:Nchannels)
380 !
390 OUTPUT @Osa;"calc:data:cwav?"
! Read in the channel wavelengths
400 ENTER @Osa;Datarray(*)
410 PRINT "Channel wavelengths"
420 PRINT Datarray(*)
430 PRINT
440 !
1-69
Amplifier Test Application
TDE Measurement Method Example Program
450 OUTPUT @Osa;"calc:data:cpow?"
! Read in the channel powers
460 ENTER @Osa;Datarray(*)
470 PRINT "Channel powers"
480 PRINT Datarray(*)
490 PRINT
500 !
510 OUTPUT @Osa;"calc:data:cga?"
! Read in the channel gains
520 ENTER @Osa;Datarray(*)
530 PRINT "Channel gains"
540 PRINT Datarray(*)
550 PRINT
560 !
570 OUTPUT @Osa;"calc:data:cnf?"
! Read in the channel noise figures
580 ENTER @Osa;Datarray(*)
590 PRINT "Channel noise figures"
600 PRINT Datarray(*)
610 PRINT
620 !
630 !***************************** Read the Test Results ********************************
640 !
650 OUTPUT @Osa;"calc:data:cst?"
! Query statistics table results
660 ENTER @Osa;Sourmwl;Sumsrcpwr;Ampmwl;Sumsamppwr
670 PRINT "Source Mean WL"
680 PRINT Sourmwl
690 PRINT
700 !
710 PRINT "Sum of Src Sig Pwr"
720 PRINT Sumsrcpwr
730 PRINT
740 !
750 PRINT "Amplifier Mean WL"
760 PRINT Ampmwl
770 PRINT
780 !
790 PRINT "Sum of Amp Sig Pwr"
800 PRINT Sumsamppwr
810 PRINT
820 !
830 !***************************** Exit the Application*********************************
840 !
850 OUTPUT @Osa;"*RST"
! Exit amplifier tde application
860 LOCAL @Osa
870 END
===========================================================
1-70
Amplifier Test Application
TDE Measurement Method Example Program
Test Results
Trigger delay
+4.65435560E-006
Number of channels
+3
Channel wavelengths
+1.55385770E-006,+1.55485825E-006,+1.55596998E-006
Channel powers
-6.17120296E+000,-8.13289990E+000,-5.85822828E+000
Channel gains
+6.64604087E-003,+3.22791498E-002,-1.66935339E-002
Channel noise figures
+4.64523752E+000,+4.87264832E+000,+4.88462994E+000
Source Mean WL
+1.55492714E-006
Sum of Src Sig Pwr
-1.83947201E+000
Amplifier Mean WL
+1.55492862E-006
Sum of Amp Sig Pwr
-1.83601805E+000
1-71
Amplifier Test Application
TDE Measurement Method Example Program
1-72
2
About the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Performing Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Setting Up a Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Characterizing DFB Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Characterizing Fabry-Perot Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Characterizing LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Source Test Application Remote Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Command Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
CALCulate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Equivalent Commands from the 71450 to the 86140B . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Sample Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Source Test Application
Source Test Application
About the Application
About the Application
The Source Test application is implemented in the Agilent 86140B series
optical spectrum analyzer (OSA). All specifications and characteristics are
derived from the 86140 series specifications.
The application quickly and accurately measures peak wavelength, power, full
width at half maximum (FWHM) and other source characteristics for
distributed feedback (DFB) lasers, Fabry-Perot (FP) lasers, and light emitting
diodes (LEDs).
When the Source Test application is launched, the selected source test (DFB,
FP, or LED) main softkey menu is displayed and changes are made to the
standard OSA screen. The Marker Display panel is overlaid with the selected
Source Test Results panel.
When in the Source Test application, all standard OSA functions are available.
You may leave the Source Test menu by selecting any desired OSA function.
Pressing the Appl’s key will always bring you back to the source test menu.
Pressing EXIT SOURCE TESTS will turn off source tests or pressing PRESET will reset
the source test settings to their default values and turn off source tests.
2-2
Source Test Application
Performing Measurements
Performing Measurements
This section explains how to start and use the Source Test application. The
application quickly and accurately measures peak wavelength, power, full
width at half maximum (FWHM) and other source characteristics for
distributed feedback (DFB) lasers, Fabry-Perot (FP) lasers, and light emitting
diodes (LEDs).
Starting the Source Test Application
1 Press the front-panel APPL’S key or, on the APPLICATIONS menu, select LAUNCH AN
INSTALLED APPLICATION. The following screen is displayed:
2-3
Source Test Application
Performing Measurements
Each installed application has an icon on the panel and a corresponding
softkey.
2 Press SOURCE TESTS to bring up the source test display, menu, and results panel
shown below.
The Source Test results panel appears in the marker area at the top of the
screen. Measurement results (attributes) for all source tests are displayed in
this panel. The currently selected source test and trace names are displayed in
the upper left corner of the results panel. Once a source test is initiated on a
given trace, it remains associated with that trace even though another trace
may be made active.
Tip: To change the selected source test trace, select the new trace (press
TRACES > ACTIVE TRACE), switch to another source test momentarily using the
Source Test softkey, and then reselect the original source test.
In addition to the source test results panel, the source test softkey menu is
also displayed with the following softkeys:
2-4
Source Test Application
Performing Measurements
Source Test is used to select the desired source test. The DFB source test is the
default test.
Bandwidth Selection is active only during the DFB source test and allows you to
change the vertical offset from the peak for the bandwidth measurement
attribute.
Measurement Setup brings up the Source Test Measurement Setup Panel.
Repeat Sweep turns continuous sweep mode on or off.
Single Sweep initiates a single sweep or turns single sweep mode on.
Exit Source Test exits the application.
All normal OSA functionality is available while in the Source Test application.
Simply select the desired function and press the APPL’S key when ready to
return to the source test application.
2-5
Source Test Application
Performing Measurements
Setting Up a Measurement
Performing a source measurement is a two step process: First you must select
the source test type for measurement (by pressing SOURCE TEST and selecting
the desired test). Next, you can specify the parameters used for the
measurement (by pressing Measurement Setup to access the Source Test
Measurement Setup panel). The most common source measurement settings
can be accessed via the setup panel. Remember that all standard OSA
functions are also available while using the Source Test application.
NOTE
Changing any of the source test measurement settings will affect the corresponding
settings in Auto Meas and Marker Setup Panels. These settings are grouped here for
convenience.
Auto Measure (Auto Meas) Span selects the wavelength span for viewing the
signal located by the auto measure function. If Auto is specified, the span is set
wide enough to display most of the signal. If a particular span is desired, clear
2-6
Source Test Application
Performing Measurements
Auto and enter the desired span in the nm text box. The recommended
selection for Auto Meas Span is Auto for FP and LED source testing and the
recommended setting for DFB source testing is 10 nm.
Auto Meas Sensitivity sets the sensitivity of the Auto Measure function so the
resulting measurement has a minimal amount of noise. It is determined by
finding the minimum in the measurement trace and comparing this value to the
known sensitivity of the instrument at that wavelength. Sensitivity is then
reduced until the signal is close to this minimum sensitivity or the sweep time
becomes too long. This function is useful when viewing high dynamic range
signals. The drawback to having this function on is that it generally requires a
longer sweep time to get better sensitivity. The default selection is off. on is
recommended for DFB lasers.
Peak Excursion (in dB) determines which side modes are included in the DFB
source test measurements. To qualify as a peak, the peak’s sides must rise and
fall by at least the peak excursion. Setting the value too high may result in not
identifying a peak. Setting the value too low may cause unwanted responses,
including noise spikes, to be identified. The default value is 3 dB. Peak
excursion is not used for the FP or LED source tests.
Peak (Pk) Density/Noise Marker Reference (Ref) Bandwidth (BW) (0.1 nm or 1.0
nm) determines whether the power spectral density is normalized to 0.1 nm or
1.0 nm. This setting is the same as the base OSA Noise Marker Reference
Bandwidth. Default value is 0.1 nm.
2-7
Source Test Application
Performing Measurements
Navigating the Source Test Measurement Setup Window
The softkeys allow you to navigate through the measurement setup panel. The
front-panel number keys, step keys, and knob on the OSA allow you to enter a
numeric value in the highlighted field.
.
The arrow softkeys allow you to navigate from field to field in the panel. The
highlighted parameter can be changed.
Select selects the highlighted parameter.
Defaults resets the parameters to their default condition.
Close Panel... saves the current setup and returns you to the previous menu.
2-8
Source Test Application
Characterizing DFB Lasers
Characterizing DFB Lasers
The DFB source test performs a series of automatic measurements on
distributed feedback lasers. All measurement results are displayed in the
Source Test Results panel across the top of the screen.
CAUTION
When you use improper cleaning and handling techniques, you risk expensive
system repairs, damaged connectors, and compromised measurements. Clean
all connectors properly before making connections. Refer to “Cleaning
Connections for Accurate Measurements” on page 5-4.
Measurement Attributes
The following is a list of attributes measured for the DFB laser source test. The
measurement attributes are displayed across the top of the display at the end
of the initial sweep. For Repeat Sweeps, the attributes are automatically
updated at the end of each sweep. In Single Sweep mode, a sweep must be
initiated in order for any setting changes to take effect and for the source test
attributes to be updated.
Peak wavelength is the wavelength at which peak amplitude occurs. Peak
wavelength is found by searching the trace from left to right across the
wavelength span looking for the highest trace point.
Mode Offset is the wavelength separation (in nanometers) between the main spectral
component and the next highest mode within the current trace span. Negative values
indicate the next highest mode lies to the left of the main mode and positive values indicate the next highest mode lies to the right of the main mode.
Stop Band is the wavelength spacing between the upper and lower side modes
adjacent to the main mode.
2-9
Source Test Application
Characterizing DFB Lasers
NOTE
If peak excursion is set too high, the Stop Band measurement will display dash lines.
Center Offset indicates how well the main mode is centered in the stop band.
This value is the difference between the wavelength of the main spectral
component and the mean of the upper and lower stop band component
wavelengths.
NOTE
If peak excursion is set too high, the Center Offset measurement will display dashed
lines.
SMSR (side mode suppression ratio) is the amplitude ratio (in dB) of the main
spectral component and the largest side mode (not necessarily the first side
mode) within the current trace. This is affected by both the wavelength span
and the peak excursion.
Peak Amplitude is the power level of the laser’s main spectral component.
Bandwidth is the bandwidth of the main spectral component of the DFB laser.
Due to the narrow line width of most DFB lasers, the result of this
measurement for an unmodulated laser is limited by the resolution bandwidth
of the optical spectrum analyzer.
2-10
Source Test Application
Characterizing DFB Lasers
To characterize a DFB laser
The following procedure is an example of a typical DFB laser measurement.
1 Press APPL’S > SOURCE TESTS > SOURCE TEST > SELECT DFB TEST to measure the
distributed feedback laser’s characteristics.
2 Press M EASUREMENT SETUP to open the Source Test Measurement Setup panel.
3 Clear the Auto Meas Span check box and enter a span of 10 nm or desired span.
4 Select ON for Auto Meas Sensitivity.
5 From the softkey menu, press CLOSE PANEL.
Tip: For turning the time and date on, press SYSTEM > MORE SYSTEM FUNCTIONS >
SET TIME/DATE. Use the navigation keys to set the date, time, and time zone that
are correct for your location. Press SET TIME/DATE when you are satisfied with
your selections. The time and date will be included on the printout.
2-11
Source Test Application
Characterizing DFB Lasers
6 Press AUTO M EAS to locate and display the laser’s response automatically.
Auto Meas locates the largest signal in the full 600 nm to 1700 nm wavelength
range, then reduces the span to display the signal properly. The reference level
is set automatically to the signal’s peak and the sensitivity is adjusted as
needed.
The source tests provide the highest level of measurement automation
possible thereby minimizing user interaction for batch source testing. For the
first device under test (DUT), Auto Meas is used to locate and display the
largest input signal, and automatically adjust all parameters (center
wavelength, reference level, display span, and sensitivity) as required by the
test. Auto Meas functionality is modified during the source tests to not turn the
marker on at the end of the Auto Meas operation. Repeat Sweep may be
disabled and Single Sweep may be selected to test subsequent devices.
At the end of the sweep, the Source Test Results panel (located at the top of
the display) displays the measurement results. For Repeat Sweeps, the results
are automatically updated at the end of each sweep. In Single Sweep mode, a
sweep must be initiated in order for any setting changes to take effect and for
the source test results to be updated.
NOTE
When you change a DFB laser source, you need to ensure that the trace is centered on
the screen. Press M ARKERS > PEAK SEARCH > MARKER TO CENTER > MARKER TO REF
LEVEL. Press APPL’S to return to the source test.
7 Press PRINT to print the results to the target printer.
2-12
Source Test Application
Characterizing DFB Lasers
Tip: To select either the internal or an external printer as the target destination,
press SYSTEM > PRINTER SETUP.
8 To save the measurement and trace data, press SAVE/RECALL > SAVE M ENU to open
the Save Setup panel.
Select the desired Save options and then press CLOSE PANEL.
For more information on saving and printing results, refer to the Agilent 86140B
Series Optical Spectrum Analyzer User’s Guide section on Save/Recall and
System menus.
NOTE
To properly characterize a DFB laser, the Sensitivity must be sufficient to resolve the
DFB’s side modes. Using Auto Meas with Auto Meas Sensitivity on ensures this. When
not using Auto Meas, be sure to use a Sensitivity setting that is sufficient to resolve side
modes of interest.
2-13
Source Test Application
Characterizing DFB Lasers
DFB Laser Measurement Techniques
This section explains how to customize and use some of the OSA functions to
assist you in accurately characterizing DFB lasers.
Setting the desired vertical offset for bandwidth measurement
One of the DFB measurements is the bandwidth of the main spectral
component. By default, the bandwidth is measured 3 dB below the peak
wavelength. To change the bandwidth, press BANDWIDTH SELECTION...from the
Source Test application’s softkey menu. At the next sweep, bandwidth will be
calculated using the new value.
2-14
Source Test Application
Characterizing DFB Lasers
The accuracy of the bandwidth measurement is affected by the following
instrument settings:
• Wavelength span
• Trace length
• Resolution bandwidth
If the wavelength span is too wide (or the bandwidth is too narrow), there may
not be enough trace points to calculate bandwidth accurately. Reducing the
span increases the accuracy of the bandwidth calculated. Increasing the trace
length also increases bandwidth accuracy.
Due to the narrow line width of most DFB lasers, the bandwidth measurement
for an unmodulated laser is the chosen resolution bandwidth of the OSA. With
modulation applied, lasers will chirp causing a spectral broadening. The
resultant displayed waveform is the composite of the OSA’s resolution
bandwidth and the modulated laser’s spectrum. When measuring the extent of
chirp on the modulated laser, choose the narrowest resolution bandwidth
available.
Using peak excursion to determine side modes
Peak Excursion (in dB) determines which side modes are included in the
measurements. To qualify as a peak, the peak’s sides must rise and fall by at
least the peak excursion. Setting the value too high may result in not
identifying a peak. Setting the value too low may cause unwanted responses,
including noise spikes, to be identified. The default value is 3 dB.
Using line markers to determine side modes
When Line Markers are enabled and the Integrate Limit is on, the source test
calculations are performed within the Line Marker limits. Note that Search
Limit and Sweep Limit do not limit the source test calculation to within the Line
Marker limits. The Line Marker limits may be adjusted to exclude modes from
the source test calculations. The Line Marker limit range is shared with total
power integration. Trace Integration need not be on to use source test with
Line Marker limits. To use Line Marker limits:
1 Press M ARKERS > M ORE M ARKER FUNCTIONS > LINE MARKER M ENU.
2 Press WAVELENGTH LINE MKR 1 and WAVELENGTH LINE MKR 2 to adjust the Line Marker
Limits.
3 Press ADVANCED LINE MKR FUNCTIONS > INTEGRATE LIMIT ON.
4 Press APPL’S to return to the Source Test.
2-15
Source Test Application
Characterizing Fabry-Perot Lasers
Characterizing Fabry-Perot Lasers
The FP source test performs a series of automatic measurements on FabryPerot lasers. All measurement results are displayed in the Source Test Results
panel across the top of the screen.
CAUTION
When you use improper cleaning and handling techniques, you risk expensive
system repairs, damaged connectors, and compromised measurements. Clean
all connectors properly before making connections. Refer to “Cleaning
Connections for Accurate Measurements” on page 5-4.
Measurement Attributes
The following is a list of attributes measured for the Fabry-Perot laser source
test. The measurement attributes are displayed across the top of the display at
the end of the initial sweep. For Repeat Sweeps, the attributes are
automatically updated at the end of each sweep. In Single Sweep mode, a
sweep must be initiated in order for any setting changes to take effect and for
the source test attributes to be updated.
Measurement attributes are calculated using the entire set of trace points in
order to provide more repeatable results. This is particularly useful for devices
that exhibit significant levels of fluctuation in the distribution of optical energy
among the spectral modes.
2-16
Source Test Application
Characterizing Fabry-Perot Lasers
Mean Wavelength represents the center of mass of the trace points, normalized
by the ratio of the trace point spacing and the resolution bandwidth. The power
and wavelength of each trace point are used to calculate the mean (FWHM)
wavelength.
n
Mean Wavelength =
∑
i=1
where:
P
------i
Po
⎛
⎞
trace point spacing ⎟
⎜ --------------------------------------------------------------------- λi
⎜
⎟
⎝ resolution bandwidth ⎠
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined below
Peak Wavelength is the wavelength of the laser’s peak spectral component.
Mode Spacing (in nm) is the average wavelength spacing between the
individual spectral components of the FP laser.
Mode Spacing (in GHz) is the average frequency between the individual spectral
components of the FP laser.
FWHM (Full Width at Half Maximum) describes the spectral width of the half-
power points of the FP laser, assuming a continuous, Gaussian power
distribution. The half-power points are those where the power spectral density
is one-half that of the peak amplitude of the computed Gaussian curve.
FWHM = 2.355σ
where:
σ is sigma as defined below
Peak Amplitude is the power level of the peak spectral component of the FP
laser.
Total Power is the summation of the power at each trace point, normalized by
the ratio of the trace point spacing and the resolution bandwidth.
⎛
⎞
trace point spacing ⎟
⎜ --------------------------------------------------------------------Pi ⎜
⎟
⎝ resolution bandwidth ⎠
i=1
n
Total Power =
∑
where:
P i is the power of a single trace point
2-17
Source Test Application
Characterizing Fabry-Perot Lasers
Sigma ( σ ) is the rms value of the spectral width of the trace points based on a
Gaussian distribution. The power and wavelength of each spectral component
is used to calculate mean wavelength.
2
P ⎛ trace point spacing ⎞
------i ⎜⎜ ----------------------------------------------------------------------⎟⎟ ( λ i – λ )
P
i = 1 o ⎝ resolution bandwidth ⎠
n
sigma =
∑
where:
λ is mean wavelength (FWHM) as defined above
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined above
2-18
Source Test Application
Characterizing Fabry-Perot Lasers
To characterize a Fabry-Perot laser
The following procedure is an example of a typical FP laser measurement.
1 Press APPL’S > SOURCE TESTS > SOURCE TEST > SELECT FP TEST to measure the FabryPerot laser’s characteristics.
2 Press M EASURE SETUP to open the Source Test Measurement Setup panel.
3 Verify that Auto Meas Span is set to Auto.
4 Press SYSTEM > MORE SYSTEM FUNCTIONS > AUTO MEASURE SETUP to verify that
Optimize Sensitivity is set to OFF.
5 From the softkey menu, press CLOSE PANEL.
Tip: For turning the time and date on, press SYSTEM > MORE SYSTEM FUNCTIONS >
SET TIME/DATE. Use the navigation keys to set the date, time, and time zone that
are correct for your location. Press SET TIME/DATE when you are satisfied with
your selections. The time and date will be included on the printout.
2-19
Source Test Application
Characterizing Fabry-Perot Lasers
6 Press AUTO M EAS to locate and display the laser’s response automatically.
Auto Meas locates the largest signal in the full 600 nm to 1700 nm wavelength
range, then reduces the span to display the signal properly. The reference level
is set automatically to the signal’s peak.
7 After Auto Meas, verify that the Sensitivity value (labeled “Sens” on the Settings
panel located at the bottom of the OSA display) is at least 27 dB below the current
signal reference level. This helps assure that accurate FP measurement attributes are
being displayed. If the sensitivity is not at least
27 dB less than the reference level, adjust the Sensitivity (press AMPLITUDE >
SENSITIVITY) to the desired level.
Tip: Sensitivity can be reduced (improving measurement quality) by either
adjusting Sensitivity directly or by using Video Bandwidth (BANDWIDTH/SWEEP
> VIDEO BW > MAN). Using Video Bandwidth has the advantage of minimizing
sweep time and averaging laser modal noise.
The source tests provide the highest level of measurement automation
possible thereby minimizing user interaction for batch source testing. For the
first device under test (DUT), Auto Meas is used to locate and display the
largest input signal, and automatically adjusts parameters (center wavelength,
reference level, and display span) as required by the test. Auto Meas
functionality is modified during source tests to not turn the marker on at the
end of the Auto Meas operation. Normally, the Marker automatically marks the
peak wavelength. Repeat Sweep may be disabled and Single Sweep may be
selected to test subsequent devices.
At the end of the sweep, the Source Test Results panel (located at the top of
the display) displays the measurement results. For Repeat Sweeps, the results
are automatically updated at the end of each sweep. In Single Sweep mode, a
sweep must be initiated in order for any setting changes to take effect and for
the source test results to be updated.
NOTE
When you change an FP laser source, you need to ensure that the trace is centered on
the screen. Press M ARKERS > PEAK SEARCH > M ARKER TO CENTER > MARKER TO REF
LEVEL. Press APPL’S to return to the source test.
2-20
Source Test Application
Characterizing Fabry-Perot Lasers
8 Press PRINT to print the results to the target printer.
Tip: To select either the internal or an external printer as the target destination,
press SYSTEM > PRINTER SETUP.
9 To save the measurement and trace data, press SAVE/RECALL > SAVE M ENU to open
the Save Setup panel.
Select the desired Save options and then press CLOSE PANEL.
For more information on saving and printing results, refer to the Agilent 86140B
Series Optical Spectrum Analyzer User’s Guide sections on Save/Recall and
System menus.
2-21
Source Test Application
Characterizing Fabry-Perot Lasers
Fabry-Perot Laser Measurement Techniques
This section explains how to customize and use some of the OSA functions to
assist you in accurately characterizing Fabry-Perot lasers.
Using line markers to select spectral modes
When Line Markers are enabled and the Integrate Limit is on, the source test
calculations are performed within the Line Marker limits. Note that Search
Limit and Sweep Limit do not limit the source test calculation to within the Line
Marker limits. The Line Marker limits may be adjusted to exclude modes from
the source test calculations. The Line Marker limit range is shared with total
power integration. Trace Integration need not be on to use source test with
Line Marker limits. To use Line Marker limits:
1 Press M ARKERS > M ORE M ARKER FUNCTIONS > LINE MARKER M ENU.
2 Press WAVELENGTH LINE MKR 1 and WAVELENGTH LINE MKR 2 to adjust the Line Marker
Limits.
3 Press ADVANCED LINE MKR FUNCTIONS > INTEGRATE LIMIT ON.
2-22
Source Test Application
Characterizing Fabry-Perot Lasers
4 Press APPL’S to return to the Source Test application.
2-23
Source Test Application
Characterizing LEDs
Characterizing LEDs
The LED source test performs a series of automatic measurements on light
emitting diodes. All measurement results are displayed in the Source Test
Results panel at the top of the screen. The LED measurement calculations
compensate for the expected change in resolution bandwidth versus
wavelength.
CAUTION
When you use improper cleaning and handling techniques, you risk expensive
system repairs, damaged connectors, and compromised measurements. Clean
all connectors properly before making connections. Refer to “Cleaning
Connections for Accurate Measurements” on page 5-4.
2-24
Source Test Application
Characterizing LEDs
Measurement Attributes
The following is a list of attributes measured for the LED source test. The
measurement attributes are displayed across the top of the display at the end
of the initial sweep. For Repeat Sweeps, the attributes are automatically
updated at the end of each sweep. In Single Sweep mode, a sweep must be
initiated in order for any setting changes to take effect and for the source test
attributes to be updated.
Mean (FWHM) represents the center of mass of the trace points, normalized by
the ratio of the trace point spacing and the resolution bandwidth. The power
and wavelength of each trace point are used to calculate the mean (FWHM)
wavelength.
n
Mean ( FWHM ) =
where:
∑
i=1
P
------i
Po
⎛
⎞
trace point spacing ⎟
⎜ --------------------------------------------------------------------- λ
⎜
⎟ i
⎝ resolution bandwidth ⎠
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined below
Mean (3dB) is the average of the two wavelengths that are 3 dB (half-power)
below the peak wavelength.
Peak Wavelength is the wavelength at which the peak of the LED spectrum
occurs.
2-25
Source Test Application
Characterizing LEDs
Sigma is the rms value of the spectral width of the LED based on a Gaussian
distribution. The power and wavelength of each spectral component are used
to calculate sigma.
2
P ⎛ trace point spacing ⎞
------i ⎜⎜ ----------------------------------------------------------------------⎟⎟ ( λ i – λ )
P
i = 1 o ⎝ resolution bandwidth ⎠
n
sigma =
∑
where:
λ is mean wavelength (FWHM) as defined below
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined below
FWHM (Full Width at Half Maximum) describes the spectral width of the half-
power (-3 dB) points of the LED, assuming a continuous, Gaussian power
distribution. The half-power points are those where the power spectral density
is one-half that of the peak amplitude of the computed Gaussian curve.
FWHM = 2.355σ
where:
σ is sigma as defined above
3 dB Width describes the spectral width of the LED based on the separation of
two wavelengths. Each wavelength has a power spectral density equal to onehalf the peak power spectral density. The 3 dB width is determined by finding
the peak of the LED spectrum, and dropping 3 dB on each side.
2-26
Source Test Application
Characterizing LEDs
Total Power is the summation of the power at each trace point, normalized by
the ratio of the trace point spacing and the resolution bandwidth. This
normalization is required because the spectrum of the LED is continuous,
rather than containing discrete spectral components (as a laser does).
⎛
⎞
⎜ trace point spacing ⎟
P i ⎜ ----------------------------------------------------------------------⎟
⎝ resolution bandwidth ⎠
i=1
n
Total Power =
∑
where:
P i is the power of a single trace point
Pk Density (0.1 nm or 1.0 nm) is the power spectral density (normalized to a
0.1 nm or 1.0 nm bandwidth) of the LED at the peak wavelength.
2-27
Source Test Application
Characterizing LEDs
To characterize an LED laser
The following procedure is an example of a typical LED laser measurement.
1 Press APPL’S > SOURCE TESTS > SOURCE TEST > SELECT LED TEST to measure the light
emitting diode’s characteristics.
2 Press M EASURE SETUP to open the Source Test Measurement Setup panel.
3 Verify the Auto Meas Span is set to Auto.
4 Verify the Optimize Sensitivity is set to OFF.
5 From the softkey menu, press CLOSE PANEL.
Tip: For turning the time and date on, press SYSTEM > MORE SYSTEM FUNCTIONS >
SET TIME/DATE. Use the navigation keys to set the date, time, and time zone that
are correct for your location. Press SET TIME/DATE when you are satisfied with
your selections. The time and date will be included on the printout.
2-28
Source Test Application
Characterizing LEDs
6 Press AUTO M EAS to locate and display the laser’s response automatically.
Auto Meas locates the largest signal in the full 600 nm to 1700 nm wavelength
range, then reduces the span to display the signal properly. The reference level
is set automatically to the signal’s peak and the sensitivity is adjusted as
needed.
The source tests provide the highest level of measurement automation
possible thereby minimizing user interaction for batch source testing. For the
first device under test (DUT), Auto Meas is used to locate and display the
largest input signal, and automatically adjust all parameters (center
wavelength, reference level, and display span) as required by the test. Auto
Meas functionality is modified during source tests to not turn the marker on at
the end of the Auto Meas operation. Normally, the Marker automatically marks
the peak wavelength. Repeat Sweep may be disabled and Single Sweep may be
selected to test subsequent devices.
At the end of the sweep, the Source Test Results panel (located at the top of
the display) displays the measurement results. For Repeat Sweeps, the results
are automatically updated at the end of each sweep. In Single Sweep mode, a
sweep must be initiated in order for any setting changes to take effect and for
the source test results to be updated.
NOTE
When you change an LED source, you need to ensure that the trace is centered on the
screen. Press M ARKERS > PEAK SEARCH > MARKER TO CENTER > MARKER TO REF LEVEL.
Press APPL’S to return to the Source Test application.
7 Press PRINT to print the results to the target printer.
Tip: To select either the internal or an external printer as the target destination,
press SYSTEM > PRINTER SETUP.
8 To save the measurement and trace data, press SAVE/RECALL > SAVE M ENU to open
the Save Setup panel.
Select the desired Save options and then press CLOSE PANEL.
For more information on saving and printing results, refer to the Agilent 86140B
Series Optical Spectrum Analyzer User’s Guide sections on Save/Recall and
System menus.
2-29
Source Test Application
Characterizing LEDs
LED Measurement Techniques
This section explains how to customize and use some of the OSA functions to
assist you in accurately characterizing LEDs.
Using line markers
When Line Markers are enabled and the Integrate Limit is on, the source test
calculations are performed within the Line Marker limits. Note that Search
Limit and Sweep Limit do not limit the source test calculation to within the Line
Marker limits. The Line Marker limits may be adjusted to include only the
desired portion of the trace in the source test calculations. The Line Marker
limit range is shared with total power integration. Trace Integration need not be
on to use the source test with Line Marker limits. To use Line Marker limits:
1 Press M ARKERS > M ORE M ARKER FUNCTIONS > LINE MARKER M ENU.
2 Press WAVELENGTH LINE MKR 1 and WAVELENGTH LINE MKR 2 to adjust the Line Marker
Limits.
3 Press ADVANCED LINE MKR FUNCTIONS > INTEGRATE LIMIT ON.
4 Press APPL’S to return to the Source Test application.
2-30
Source Test Application
Source Test Application Remote Commands
Source Test Application Remote Commands
The CALC: section of the Agilent 86140B Series Optical Spectrum Analyzer
User’s Guide provides detailed information on remote programming of the
instrument. Only commands unique to the Source Test application are included
in this chapter with the following exceptions:
Center of Mass, Sigma, and FWHM calculations are supported via remote
commands without entering the Source Test application. These commands are
documented below and also in the Remote Operation chapter in the Agilent
86140B Series Optical Spectrum Analyzer User’s Guide.
NOTE
Launching another OSA application remotely, such as Passive Component Test, will
automatically disable any active source test. Initiating a source test from within another
application is not supported.
2-31
Source Test Application
Source Test Application Remote Commands
Command Conventions
Table 1
Convention
Description
<>
Angle brackets indicate text strings entered by the developer.
[]
Square brackets indicate that the keyword DEFAULT can be used instead
of a value or a variable for that parameter. Refer to the actual command
description for the behavior when the DEFAULT keyword is used for a
parameter.
|
Indicates a choice of one element from a list.
{}
Braces indicate a group of constants to select from. Each constant is
separated by the | character.
name
Indicates the variable for which you provide a descriptive name. Any letter
(Aa-Zz) followed by letters, digits (0-9) and underscore (_). Only the first 32
characters are significant.
spec_min
–infinity. The parameter spec_min cannot be a variable, only a constant or
DEFAULT.
spec_max
+infinity. The parameter spec_max cannot be a variable, only a constant or
DEFAULT.
from
Start wavelength or frequency of trace in nm (default) or THz.
to
Stop wavelength or frequency of trace in nm (default) or THz.
excursion
+excursion: means excursion dBs up (for example, from a pit).
-excursion: means excursion dBs down (for example, from a peak).
ref_pt
The reference point to be used for a measurement keyword.
2-32
Source Test Application
Source Test Application Remote Commands
CALCulate Subsystem Commands
The CALCulate subsystem performs post-acquisition data processing. The
CALCulate subsystem operates on data acquired by a SENSe function.
Trace A corresponds to CALC 1, Trace B corresponds to CALC 2, and so on. Only
one of each calculation (that is, Source Test, Center of Mass, or FWHM) may be
on. For example, if FWHM is on for Trace A, turning FWHM on for Trace B will
disable the FWHM for Trace A.
CALCulate[1|2|3|4|5|6]:SOURce:TEST DFB | FP | LED | OFF
CALCulate[1|2|3|4|5|6]:SOURce:TEST?
Initiates a source test measurement or disables the active suite. Only a single
measurement suite may be on at a time (also operates exclusively with
applications: Passive Component Test (PCT), Wavelength Division Multiplexing
(WDM), and Amplifier Test applications). off disables all suites. Calculations
are performed at the end of each sweep.
CALCulate[1|2|3|4|5|6]:SOURce:[DATA]?
Retrieves the results of the currently active source test measurement suite.
The data is returned in either ASCII or binary form as determined by the
FORMat:DATA command. Requesting results from a trace not selected in the
CALCulate[1|2|3|4|5|6]:SOURce:TEST command returns a “Settings
conflict” error.
Error values are indicated by returning the number: 9.91e+37. This value is
defined by the SCPI standard to represent NaN (not a number). This indicates
that the source test was unable to perform the particular measurement.
Results will be returned in the order as shown below.
2-33
Source Test Application
Source Test Application Remote Commands
Table 2 Source Test Measurement Parameters
Source Test
Measurement Parameter
Units
DFB Test
Peak Wavelength
Meters
Mode Offset
Meters
Stop Band
Meters
Center Offset
Meters
SMSR
dB
Peak Amplitude
dBm
Bandwidth
Meters
Bandwidth Amplitude
dB
Mean Wavelength
Meters
Peak Wavelength
Meters
Mode Spacing (M)
Meters
Mode Spacing (Hz)
Hertz
FWHM
Meters
Peak Amplitude
dBm
Total Power
dBm
Sigma
Meters
Mean (FWHM) Wavelength
Meters
Mean Wavelength (3 dB down)
Meters
Peak Wavelength
Meters
Sigma
Meters
FWHM
Meters
Width at 3 dB down
Meters
Total Power
dBm
Peak Spectral Density (1.0 nm or 0.1 nm)
depending on Noise Marker Reference
Bandwidth
dBm
FP Test
LED Test
2-34
Source Test Application
Source Test Application Remote Commands
CALCulate:SOURce:FUNCtion:BWIDth | BANDwidth:NDB <numeric_value>
CALCulate:SOURce:FUNCtion:BWIDth | BANDwidth:NDB?
Sets the desired vertical offset from the peak wavelength for the DFB source
test bandwidth calculation. The default value is -3 dB. The parameter units are
as specified in the UNIT:RATio command. This value can be set or queried
anytime. The DFB source test does not need to be on. The new bandwidth
value will be used on the next sweep. The offset value applies to all DFB source
test bandwidth calculations.
CALCulate[1|2|3|4|5|6]:CENTermass:STATe OFF | ON | 0 | 1
Turns the Center of Mass (Mean Wavelength) calculation on. Trace A
corresponds to CALC 1, Trace B corresponds to CALC 2, and so on. Only one
Center of Mass calculation may be on. For instance, if Center of Mass is on for
Trace A, turning Center of Mass on for Trace B will disable the Center of Mass
calculation for Trace A. The data is returned in either ASCII or binary form as
determined by the FORMat:DATA command.
The Center of Mass of the trace points is normalized by the ratio of the trace
point spacing and the resolution bandwidth. The power and wavelength of
each trace point are used to calculate the Center of Mass. The formula used is:
n
Center of Mass =
∑
i=1
P
------i
Po
⎛
⎞
trace point spacing ⎟
⎜ --------------------------------------------------------------------- λ
⎜
⎟ i
⎝ resolution bandwidth ⎠
where:
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined below
2-35
Source Test Application
Source Test Application Remote Commands
Total Power is the summation of the power at each trace point, normalized by
the ratio of the trace point spacing and the resolution bandwidth. The formula
used is:
⎛
⎞
trace point spacing ⎟
⎜ --------------------------------------------------------------------Pi ⎜
⎟
⎝ resolution bandwidth ⎠
i=1
n
Total Power =
∑
where:
P i is the power of a single trace point
CALCulate[1|2|3|4|5|6]:CENTermass:[DATA]?
Returns the Center of Mass calculation results in meters. Trace A corresponds
to CALC 1, Trace B corresponds to CALC 2, and so on. Corrections to all
calculations are made for the slope and variation of the resolution bandwidth
filter over the wavelength range of the trace. When
CALCulate:TPOWer:IRANge is on, the calculation is performed over the upper
and lower range limits. All calculations (that is, SOURce, CENTermass, FWHM,
SIGMA, and TPOWer) share the same line marker limits. Sending this query
when the CALCulate:CENTermass:STATe is off will generate a “Settings
conflict” error. If the Center of Mass calculation cannot be performed, the
number 9.91e+37 is returned. This value is defined by the SCPI standard to
represent NaN (not a number).
CALCulate[1|2|3|4|5|6]:FWHM:STATe OFF | ON | 0 | 1
Turns the Full Width Half Maximum (FWHM) calculation on. Trace A
corresponds to CALC 1, Trace B corresponds to CALC 2, and so on. Only one of
each calculation may be on. For instance if FWHM is on for Trace A, turning
FWHM on for Trace B will disable the FWHM calculation for Trace A. The data
is returned in either ASCII or binary form as determined by the FORMat:DATA
command.
FWHM (Full Width at Half Maximum) describes the spectral width of the half-
power (-3 dB) points of the trace, assuming a continuous, Gaussian power
distribution. The half-power points are those where the power spectral density
is one-half that of the peak amplitude. The formula used is:
FWHM = 2.355σ
where: σ is sigma as defined in CALCulate:SIGMa
2-36
Source Test Application
Source Test Application Remote Commands
CALCulate[1|2|3|4|5|6]:FWHM: [DATA]?
Returns the FWHM calculation results in meters. Trace A corresponds to CALC
1, Trace B corresponds to CALC 2, and so on. Corrections to all calculations are
made for the slope and variation of the resolution bandwidth filter over the
wavelength range of the trace. When CALCulate:TPOWer:IRANge is on, the
calculation is performed over the upper and lower range limits. All calculations
(that is, SOURce, CENTermass, FWHM, SIGMA, and TPOWer) share the same
line marker limits. Sending this query when the CALCulate:FWHM:STATe is off
will generate a “Settings conflict” error. If the FWHM calculation cannot be
performed, the number 9.91e+37 is returned. This value is defined by the SCPI
standard to represent NaN (not a number).
CALCulate[1|2|3|4|5|6]:SIGMa: [DATA]?
Returns the sigma calculation results in meters.
Sigma is the rms value of the spectral width of the trace points based on a
Gaussian distribution. The power and wavelength of each spectral component
is used to calculate mean wavelength.
2
P ⎛ trace point spacing ⎞
------i ⎜ ----------------------------------------------------------------------⎟ ( λ i – λ )
⎜
⎟
P
i = 1 o ⎝ resolution bandwidth ⎠
n
sigma =
where:
∑
λ is mean wavelength (Center of Mass) as defined in CALC:CENT
λ i is the wavelength of a single trace point
P i is the power of a single trace point
P o is total power as defined in CALC:CENT
2-37
Source Test Application
Source Test Application Remote Commands
CALCulate:FWHM:STATe must be on for this query. Trace A corresponds to
CALC 1, Trace B corresponds to CALC 2, and so on. Corrections to all
calculations are made for the slope and variation of the resolution bandwidth
filter over the wavelength range of the trace. When
CALCulate:TPOWer:IRANge is on, the calculation is performed over the upper
and lower range limits. All five common calculation ranges (that is, SOURce,
CENTermass, FWHM, SIGMA, and TPOWer) share the same limits. Sending a
CALCulate:SIGMa? query when the CALCulate:FWHM:STATe is off will
generate a “Settings conflict” error. If the Sigma calculation cannot be
performed, the number 9.91e+37 is returned. This value is defined by the SCPI
standard to represent NaN (not a number).
CALCulate[1|2|3|4|5|6]:TPOWer:IRANge:LOWer
<numeric_value>[M|UM|NM|A|HZ|KHZ|MHZ|GHZ|THZ]
CALCulate[1|2|3|4|5|6]:TPOWer:IRANge:LOWer?
Sets the lower X-axis limit range for the TPOWer, SOURce, CENTermass,
FWHM, and SIGMa calculations for all traces. Setting this value when the
CALCulate:TPOWer:IRANge[:STATe] is off will automatically turn the
CALCulate:TPOWer:IRANge[:STATe] on. The range used for the total power
integration is the same range used for the marker search range, the trace mean
range, and the wavelength range. Changing the range with this command will
change all four ranges.
Default units for the parameter are meters. Sending the command when the
instrument is in a zero span will generate a “Settings conflict” error.
CALCulate[1|2|3|4|5|6]:TPOWer:IRANge:UPPer
<numeric_value>[M|UM|NM|A|HZ|KHZ|MHZ|GHZ|THZ]
CALCulate[1|2|3|4|5|6]:TPOWer:IRANge:UPPer?
Sets the upper X-axis limit range for the TPOWer, SOURce, CENTermass,
FWHM, and SIGMa calculations for all traces. Setting this value when the
CALCulate:TPOWer:IRANge[:STATe] is off will automatically turn the
CALCulate:TPOWer:IRANge[:STATe] on. The range used for the total power
calculation is the same range used for the marker search range, the trace mean
range and the wavelength range. Changing the range with this command will
change all four ranges.
2-38
Source Test Application
Source Test Application Remote Commands
Default units for the parameter are meters. Sending the command when the
instrument is in a zero span will generate a “Settings conflict” error.
CALCulate:MARKer:FUNCtion:NOISe:BWIDth|BANDwidth <numeric_value>
CALCulate:MARKer:FUNCtion:NOISe:BWIDth|BANDwidth?
Sets the normalization bandwidth for the marker noise result query and the
LED source test peak density calculation. The default units for the parameter
are meters. There are only two allowable settings: 1.0 nm and 0.1 nm. Sending
any value outside this range will generate a "Data out of range" error. Sending
a value within this range will set the bandwidth to whichever of the two
possible settings is closest to the specified value.
2-39
Source Test Application
Source Test Application Remote Commands
CALibration Subsystem Commands
This subsystem has the function of performing system calibration.
CALibration Alignment
Performs an automatic alignment of the instrument at the wavelength of the
largest signal found in full span. This aligns the monochromator output with
the photodetector for improved amplitude accuracy. Sending this command
with a marker on screen will generate a Settings conflict error.
Syntax
CAL:ALIG
Related Key
Auto Align
2-40
Source Test Application
Source Test Application Remote Commands
Equivalent Commands from the 71450 to the 86140B
The following table provides a list of the Agilent 71450 series commands and
the SCPI equivalent commands for the Agilent 86140B series analyzers. The
results are returned in the same order as Table 2 on page 2-34.
NOTE: For the 86140B series OSA, any space(s) or characters between a token
(_) and the query (?) symbol are not supported. For example:
FP_ ? will not work on the 86140B series OSA, but will work for the
71450 series OSA. FP_? will work on the 86140B series OSA.
NOTE
All legacy source test commands operate on the currently active trace.
2-41
Source Test Application
Source Test Application Remote Commands
Table 3 Equivalent Commands from the 71450 to the 86140B
71450 Series
Command
DFB Command
86140B Series Command
Description
DFB_
CALCulate:SOURce:TEST DFB
DFB_?
CALCulate:SOURce:[DATA]?
DFB_B
Not supported
DFB_C
Not supported
DFB_O
Not supported, use
CALCulate:SOURce:TEST OFF
CALCulate:SOURce:TEST OFF
Start DFB laser source
test
Return DFB
measurement suite
results
Turn stop band peaks
view ON or OFF
Turn SMSR view ON
or OFF
Turn calculation ON or
OFF
Exit DFB laser source
test
Enable Sensitivity
Optimization function
DFB_Q
DFB_Z
DISP:WIND:TRAC:ALL:SCALE:
AUTO:OPT prior to Auto Meas
FP Command
FP_
CALCulate:SOURce:TEST FP
FP_?
CALCulate:SOURce:[DATA]?
FP_B
Not supported
FP_C
Not supported
FP_G
Not supported
FP_K
Default
FP_L
Not supported
2-42
Start FP laser source
test
Return FP
measurement suite
results
Turn peaks view ON or
OFF
Turn distribution view
ON or OFF
Select envelope
distribution
Select Gaussian
distribution
Select Lorenzian
distribution
Source Test Application
Source Test Application Remote Commands
71450 Series
Command
86140B Series Command
Description
FP_MKBW
Not supported
FP_O
FP_Q
Not supported, use
CALCulate:SOURce:TEST OFF
CALCulate:SOURce:TEST OFF
FP_TH
Not supported
Set envelope
bandwidth amplitude
Turn calculation ON or
OFF
Exit FP laser source
test
Set Peak Threshold
LED Command
LED_
CALCulate:SOURce:TEST LED
LED_?
CALCulate:SOURce:[DATA]?
LED_B
Not supported
LED_C
Not supported
LED_K
Default
LED_L
Not supported
LED_O
Not supported, use
CALCulate:SOURce:TEST OFF
CALCulate:SOURce:TEST OFF
LED_Q
Start LED laser source
test
Return LED
measurement suite
results
Turn integration
window trace ON or
OFF
Turn distribution view
ON or OFF
Select Gaussian
distribution
Select Lorenzian
distribution
Turn calculation ON or
OFF
Exit LED laser source
test
Sample Programs
The following are sample programs for the Source Test measurement, DFB, FP
and LED remote control commands.
2-43
Source Test Application
Source Test Application Remote Commands
Source Test measurements sample commands
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
! Program to demonstrate the new commands for source measurements.
! The center of mass and FWHM routines are used to measure LED source.
!
! re-store "newcommands"
!
ASSIGN @Osa TO 723;EOL CHR$(12) END
! Set command terminator to LF & EOI
!
PRINTER IS "results.txt"
!
! *** Setup OSA for measurement ***
!
OUTPUT @Osa;"*rst"
! Preset OSA
!
OUTPUT @Osa;"sens:wav:star 1440nm"
! Set start wavelength
OUTPUT @Osa;"sens:wav:stop 1660nm"
! Set stop wavelength
!
OUTPUT @Osa;"disp:wind:trac:y1:scal:rlev -20.0dbm"
! Set reference level
OUTPUT @Osa;"sens:pow:dc:rang:low -60dbm"
! Set sensitivity required
OUTPUT @Osa;"sens:bwid:res 5nm"
! Set resolution bandwidth
!
OUTPUT @Osa;"calc:cent:stat on"
!Enable center of mass measurement
OUTPUT @Osa;"calc:fwhm:stat on"
! Enable FWHM measurement
!
! *** Initiate measurement ***
!
OUTPUT @Osa;"init:imm"
! Take sweep to update display
!
OUTPUT @Osa;"calc:cent?
! Request mean WL
ENTER @Osa;Meanwl
OUTPUT @Osa;"calc:fwhm?"
! Request FWHM
ENTER @Osa;Fwhm
OUTPUT @Osa;"calc:sigma?"
! Request sigma
ENTER @Osa;Sigma
!
! *** Print measurement results ***
!
PRINT
PRINT "Command Measurement results"
PRINT
PRINT "Mean Wavelength (m)",Meanwl
PRINT "FWHM (m)",Fwhm
PRINT "Sigma (m)",Sigma
!
OUTPUT @Osa;"calc:cent:stat off"
! Turn off measurement
OUTPUT @Osa;"calc:Fwhm:stat off"
! Turn off measurement
!
LOCAL @Osa
! Release OSA to local control
!
END
Command Measurement results
Mean Wavelength (m) 1.55280884E-6
FWHM (m) 5.41096035E-8
Sigma (m) 2.29764771E-8
2-44
Source Test Application
Source Test Application Remote Commands
DFB Sample Remote Control Commands:
10 ! Program to demonstrate remote control of the source application.
20 ! The measurement is completed and the data returned.
30 !
40 ! re-store "DFBsource"
50 !
60 ASSIGN @Osa TO 723;EOL CHR$(12) END
! Set command terminator to LF & EOI
70 !
80 ! PRINTER IS "results.txt"
90 !
100 ! *** Setup OSA for measurement ***
110 !
120 OUTPUT @Osa;"*rst"
! Preset OSA
130 OUTPUT @Osa;"calc:sour:test dfb"
! Select DFB source measurement
140 !
150 OUTPUT @Osa;"sens:wav:cent 1562nm"
! Set center frequency and span
160 OUTPUT @Osa;"sens:wav:span 20nm"
! for typical measurement
170 !
180 OUTPUT @Osa;"disp:wind:trac:y1:scal:rlev 0dbm" ! Set reference level
190 OUTPUT @Osa;"sens:pow:dc:rang:low -60dbm"
! Set sensitivity required
200 OUTPUT @Osa;"sens:bwid:res 0.1nm"
! Set resolution bandwidth
210 !
220 OUTPUT @Osa;"calc:mark:pexc:peak 3.0db"
! Set peak excursion
230 OUTPUT @Osa;"calc:sour:func:bwid:ndb -6.0db" ! Set vertical offset for BW
240 !
250 ! *** Initiate measurement ***
260 !
270 OUTPUT @Osa;"init:imm"
! Take sweep to update display
280 !
290 OUTPUT @Osa;"calc:sour?"
! Request measurement data
300 ENTER @Osa;Peakwl,Moffs,Stopb,Coffs,Smsr,Peaka,Bw,Bwamp
310 !
320 ! *** Print measurement results ***
330 !
340 PRINT
350 PRINT "DFB Measurement results"
360 PRINT
370 PRINT "Peak Wavelength (m)",Peakwl
380 PRINT "Mode Offset (m)",Moffs
390 PRINT "Stop Band (m)",Stopb
400 PRINT "Center Offset",Coffs
410 PRINT "SMSR (dB)",Smsr
420 PRINT "Peak Amplitude (dBm)",Peaka
430 PRINT "Bandwidth (m)",Bw
440 PRINT "Bandwidth Amplitude (dB)",Bwamp
450 !
460 OUTPUT @Osa;"calc:sour:test off"
! Turn off source measurement
470 !
480 LOCAL @Osa
! Release OSA to local control
490 !
500 END
2-45
Source Test Application
Source Test Application Remote Commands
DFB Measurement results
Peak Wavelength (m) 1.56194E-6
Mode Offset (m) -9.4E-10
Stop Band (m)
2.26E-9
Center Offset
-1.9E-10
SMSR (dB) 39.7615558
Peak Amplitude (dBm)-.538451274
Bandwidth (m)
1.4E-10
Bandwidth Amplitude (dB) -6
2-46
Source Test Application
Source Test Application Remote Commands
FP Sample Remote Control Commands
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
! Program to demonstrate remote control of the source application.
! The measurement is completed and the data returned.
!
! re-store "FPsource"
!
ASSIGN @Osa TO 723;EOL CHR$(12) END
! Set command terminator to LF & EOI
PRINTER IS "results.txt"
!
! *** Setup OSA for measurement ***
!
OUTPUT @Osa;"*rst"
! Preset OSA
OUTPUT @Osa;"calc:sour:test fp"
! Select FP source measurement
!
OUTPUT @Osa;"sens:wav:star 1540nm"
! Set start wavelength
OUTPUT @Osa;"sens:wav:stop 1560nm"
! Set stop wavelength
!
OUTPUT @Osa;"disp:wind:trac:y1:scal:rlev -10.0dbm"! Set reference level
OUTPUT @Osa;"sens:pow:dc:rang:low -60dbm"
! Set sensitivity required
OUTPUT @Osa;"sens:bwid:res 0.2nm"
! Set resolution bandwidth
!
! *** Initiate measurement ***
!
OUTPUT @Osa;"init:imm"
! Take sweep to update display
!
OUTPUT @Osa;"calc:sour?
! Request measurement data
ENTER @Osa;Meanwl,Peakwl,Modespm,Modesph,Fwhm,Peaka,Tpow,Sigma
!
! *** Print measurement results ***
!
PRINT
PRINT "FP Measurement results"
PRINT
PRINT "Mean Wavelength (m)",Meanwl
PRINT "Peak Wavelength (m)",Peakwl
PRINT "Mode Spacing (m)",Modespm
PRINT "Mode Spacing (Hz)",Modesph
PRINT "FWHM (m)",Fwhm
PRINT "Peak Amplitude (dBm)",Peaka
PRINT "Total Power (dBm)",Tpow
PRINT "Sigma (m)",Sigma
!
OUTPUT @Osa;"calc:sour:test off"
! Turn off source measurement
!
LOCAL @Osa
! Release OSA to local control
!
END
2-47
Source Test Application
Source Test Application Remote Commands
FP Measurement results
Mean Wavelength (m) 1.54976934E-6
Peak Wavelength (m) 1.55002E-6
Mode Spacing (m) 1.13777778E-9
Mode Spacing (Hz) 1.42018207E+11
FWHM (m) 2.86935505E-9
3 dB Width (m)
0
Peak Amplitude (dBm)-9.93317222
Total Power (dBm) -9.12593026
Sigma (m) 1.21840979E-9
2-48
Source Test Application
Source Test Application Remote Commands
2-49
Source Test Application
Source Test Application Remote Commands
LED Sample Remote Control Commands
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
2-50
! Program to demonstrate remote control of the source application.
! The measurement is completed and the data returned.
!
! re-store "LEDsource"
!
ASSIGN @Osa TO 723;EOL CHR$(12) END
! Set command terminator to LF & EOI
!
PRINTER IS "results.txt"
!
! *** Setup OSA for measurement ***
!
OUTPUT @Osa;"*rst"
! Preset OSA
OUTPUT @Osa;"calc:sour:test led"
! Select LED source measurement
!
OUTPUT @Osa;"sens:wav:star 1440nm"
! Set start wavelength
OUTPUT @Osa;"sens:wav:stop 1660nm"
! Set stop wavelength
!
OUTPUT @Osa;"disp:wind:trac:y1:scal:rlev -20.0dbm" ! Set reference level
OUTPUT @Osa;"sens:pow:dc:rang:low -60dbm"
! Set sensitivity required
OUTPUT @Osa;"sens:bwid:res 5nm"
! Set resolution bandwidth
OUTPUT @Osa;"calc:mark:func:nois:band 1nm"
! Set noise reference to 1 nm
!
! *** Initiate measurement ***
!
OUTPUT @Osa;"init:imm"
! Take sweep to update display
!
OUTPUT @Osa;"calc:sour?"
! Request measurement data
ENTER @Osa;Meanwlf,Meanwl,Peakwl,Sigma,Fwhm,Bwidth,Tpow,Peaksd
!
! *** Print measurement results ***
!
PRINT
PRINT "LED Measurement results"
PRINT
PRINT "Mean (FWHM) Wavelength (m)",Meanwlf
PRINT "Mean Wavelength (m)",Meanwl
PRINT "Peak Wavelength (m)",Peakwl
PRINT "Sigma (m)",Sigma
PRINT "FWHM (m)",Fwhm
PRINT "3 dB Width (m)",Bwidth
PRINT "Total Power (dBm)",Tpow
PRINT "Peak Spectral Density (dBm)",Peaksd
!
OUTPUT @Osa;"calc:sour:test off"
! Turn off source measurement
!
LOCAL @Osa
! Release OSA to local control
!
END
Source Test Application
Source Test Application Remote Commands
LED Measurement results
Mean (FWHM) Wavelength (m) 1.55273635E-6
Mean Wavelength (m) 1.55099E-6
Peak Wavelength (m) 1.55E-6
Sigma (m) 2.29537883E-8
FWHM (m) 5.40561714E-8
3 dB Width (m)
4.862E-8
Total Power (dBm) -10.333219
Peak Spectral Density (dBm) -27.5968118
2-51
Source Test Application
Source Test Application Remote Commands
2-52
3
About the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
The Passive Component Test Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Performing Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Designing Specification Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Excel Template Wizard for the PCT Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Specification Set Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Specification Set Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Passive Component Test Remote Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Command Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
CALCulate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
DISPlay Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
FORMat Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
HCOPy Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
INITiate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
MMEMory Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
SENSe Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
TRACe Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Sample Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Passive Component Test Application
Passive Component Test Application
About the Application
About the Application
The Passive Component Test application simplifies the complex
characterization and testing of passive components. The application includes
guided setups to prompt you through the measurement procedure. When the
setup is complete the application performs an automatic pass/fail check
against your custom specifications.
The application can easily be customized for your particular devices by
modifying the specification files using either a text editor or a Microsoft®1
Excel spreadsheet template wizard. The template wizard can be downloaded
from the web. For more information, refer to “Excel Template Wizard for the
PCT Application” on page 3-23.
To perform a measurement, you must run a specification file. Specification files
configure the settings of the instrument, describe measurements, and direct
the printing or saving of the measurement results. Specification files can be
stored and loaded from the internal memory of the optical spectrum analyzer, or
imported from a disk.
Because specification sets are stored in the internal memory of the optical
spectrum analyzer, you can easily switch between tests. Refer to “Designing
Specification Sets” on page 3-22 to learn how to design your own specification
files.
It is easy to learn how to design and write specification files. Anyone with a
basic understanding of how to operate the optical spectrum analyzer can learn
how to design specification sets in approximately one hour. This is a small
investment considering the time you’ll save testing your devices.
Figure 1 and Figure 2 on page 3-4 show the measurement screen and the table
of results displayed after a measurement has been taken.
1. Microsoft® is a U.S. registered trademark of Microsoft Corp.
3-2
Passive Component Test Application
About the Application
Figure 1 The Measurement screen
3-3
Passive Component Test Application
About the Application
Figure 2 A table of results
3-4
Passive Component Test Application
About the Application
The Passive Component Test Menus
The application softkeys are accessed using the front-panel APPL’S key or the
Applications menu, Launch an Installed Application selection on the menu bar.
3-5
Passive Component Test Application
Performing Measurements
Performing Measurements
This section explains how to load and use the Passive Components Test
application.
Measurements are performed using either the instrument’s internal broadband
EELED or white-light source, or an external broadband source. You can test
passive devices having any number of light paths, such as filters and couplers
and WDM multiplexers.
To use the Passive Components Test application you must:
1 Start the application, see “To start the Passive Components Test application” on page
3-7.
2 Load a specification set from internal memory, see “To load an existing specification
set” on page 3-11, or import a specification set from a floppy disk, see “To import a
specification set” on page 3-9.
3 Perform a normalization if required, see “To run the source normalization routines”
on page 3-13. The application automatically detects whether normalization is
required.
4 Measure the device under test, see “To measure the device under test” on page 3-14.
You can then:
• Save the results, see “To save the results to floppy” on page 3-15.
• Print the results, see “To print the results” on page 3-15.
• View the results in a table, see “To display a table of the results” on page 3-16.
3-6
Passive Component Test Application
Performing Measurements
To start the Passive Components Test application
1 Press the front-panel APPL’S key or the Applications menu Launch an Installed
Application selection.
2 The following screen is displayed.
Figure 3 Applications Panel and Menu
The panel and the menu change whenever an application is installed or
uninstalled. Each installed application has an icon on the panel and a
corresponding softkey.
3 Press the PASSIVE COMPONENTS softkey. The loading of the application is indicated by
the on-screen message, “Loading Passive Component Application, Please Wait...”.
When the application is loaded, the name of the selected set appears on the SPEC
SET.... softkey. The application is now ready for use.
The following functions assume the application is loaded.
3-7
Passive Component Test Application
Performing Measurements
To select a specification set
1 Press the SPEC SET.... <SPEC SET> softkey.
You can now load an existing specification set, import a new specification set
from a floppy disk, or delete an existing specification set from the internal
memory of the OSA. If no specification sets are available, the default
specification set is loaded.
3-8
Passive Component Test Application
Performing Measurements
To import a specification set
1 Insert the floppy disk containing the specification set into the internal floppy disk
drive of the OSA.
2 Press the SPEC SET.... <SPEC SET> softkey.
NOTE
Specification set file names must conform to the MS-DOS 8.3 file name convention, a
maximum of 8 characters.
3 Press the IMPORT SPEC SET.... softkey.
A list of the externally stored specification sets is displayed.
4 Use the navigation keys to select the desired specification set.
5 Press the IMPORT SET softkey.
The selected specification set is imported into the internal memory of the OSA.
When a specification set is imported it is checked for errors and “compiled”
before being copied into internal storage.
3-9
Passive Component Test Application
Performing Measurements
If errors are detected in the specification set being imported, the SHOW
WARNINGS.... softkey appears. Press the SHOW WARNINGS.... softkey, then the PREV
and NEXT softkeys to display a detailed description of the error.
If no errors are detected, the file is automatically copied to internal memory,
loaded, and the application returns to the previous menu.
3-10
Passive Component Test Application
Performing Measurements
To load an existing specification set
1 Press the SPEC SET.... <SPEC SET> softkey.
2 Press the LOAD SPEC SET.... softkey.
A list of the internally stored specification sets is displayed. A specification set
must be imported from a floppy disk into the internal memory of the OSA before
it can be loaded. For information on importing specification sets, see “To import
a specification set” on page 3-9.
If no specification sets have been previously imported, the Load Spec Set list
will contain the Default specification set.
3 Use the navigation keys to select the desired specification set.
4 Press the LOAD SET softkey.
The currently selected specification set is loaded and you are returned to the
previous softkey menu. While the specification set is being loaded, the
message “Loading Spec Set <spec set name>, Please Wait...” is displayed.
3-11
Passive Component Test Application
Performing Measurements
To export a specification set
1 Press the SPEC SET.... <SPEC SET> softkey.
2 Press the EXPORT SPEC SET.... softkey. A list of the internally stored specification sets
is displayed.
3 Use the navigation keys to select the desired specification set and then press the
EXPORT SET softkey. The CSV specification set file from internal memory is output to
the floppy disk.
To delete a specification set
1 Press the SPEC SET.... <SPEC SET> softkey.
2 Press the DELETE SPEC SET.... softkey. A list of the internally stored specification sets
is displayed.
3 Use the navigation keys to select the specification set to be deleted and then press
the DELETE SPEC SET softkey. The currently selected specification set is deleted from
internal memory. After the file is deleted, the application returns to the previous
menu.
3-12
Passive Component Test Application
Performing Measurements
To run the source normalization routines
NOTE
The application will automatically detect if a normalization is required and will run the
routine before the next measurement is made. The time interval between
normalizations is specified in the specification set.
1 Load the desired specification set. See “To select a specification set” on page 3-8.
2 Press the PREVIOUS MENU softkey.
3 Press the NORMALIZE REFERENCE softkey.
4 Follow the on-screen instructions to perform the source normalization.
After the source normalization is successfully completed, press Continue to return to
the previous menu. The device under test can be measured. See “To measure the
device under test” on page 3-14.
3-13
Passive Component Test Application
Performing Measurements
To measure the device under test
1 Load the desired specification set. See “To select a specification set” on page 3-8.
2 Press the MEASURE <SPEC SET> softkey. The application will detect and automatically
run the normalization routine if required. See “To run the source normalization
routines” on page 3-13.
3 The measurement will automatically continue when the normalization routine is
completed.
The results can now be viewed as a waveform, as shown in the figure, or in a
table, see “To display a table of the results” on page 3-16. The data can also be
saved, see “To save the results to floppy” on page 3-15, and printed, see “To
print the results” on page 3-15.
3-14
Passive Component Test Application
Performing Measurements
To save the results to floppy
The results can be saved automatically by using the STORE, AUTO keyword in
the specification set, refer to “STORE, AUTO” on page 3-68.
To save the results manually after completing a measurement, press the
DOCUMENT RESULTS softkey. Then press the SAVE RESULTS TO FLOPPY softkey. The
results of the test are saved to the floppy disk. The data can be saved as either
graphical data in CGM format or as tabular data in CSV. For information on
selecting the type of data to be saved, see “To change the default application
settings” on page 3-19.
To print the results
The results can be printed automatically by using the PRINT keyword in the
specification set, refer to “PRINT” on page 3-66.
To print the results manually after completing a measurement, press the
DOCUMENT RESULTS softkey. Then press the PRINT RESULTS softkey. The results can
be printed out as a graph, a table, or as both on either the internal printer or on
an external printer. See “To change the default application settings” on
page 3-19 for information on making these selections.
3-15
Passive Component Test Application
Performing Measurements
To display a table of the results
After a measurement has been completed, press the DISPLAY TABLE.... softkey.
3-16
Passive Component Test Application
Performing Measurements
To edit the ID of the device under test
NOTE
Based on the specification set selected, you are usually prompted for the Device ID and
Comments at the beginning of the measurement. However, if you were not prompted, or
you wish to edit the Device ID or Comment fields, the following procedure can be used.
1 After completing a measurement, press the DOCUMENT RESULTS.... softkey.
2 Press the EDIT ID.... softkey.
To enter the ID using the arrow keys
1 Use the front-panel step keys (
and ⇓) and the arrow softkeys (→ and ←) to
highlight each letter of the ID string.
2 When the desired letter or function is selected, press the SELECT softkey.
3 Select the BACKSPACE softkey to delete individual letters.
4 When you finish entering the string, press the CONTINUE softkey.
To enter the ID using a trackball or mouse
1 Use the pointing device to place the cursor on a letter of the filename. Click on the
character to select it.
2 Click the BACKSPACE softkey to delete individual letters.
3 When you finish entering the string, click the CONTINUE softkey. The new device ID is
displayed on-screen in the ID field.
NOTE
The new Device ID is saved only for the current session. Each time a new device is
measured, the comment and ID strings are reset to the values specified in the
specification set.
3-17
Passive Component Test Application
Performing Measurements
To edit the comments for the device under test
NOTE
Based on the specification set selected, you are usually prompted for the Device ID and
Comments at the beginning of the measurement. However, if you were not prompted, or
you wish to edit the Device ID or Comment fields, the following procedure can be used.
1 After completing a measurement, press the DOCUMENT RESULTS.... softkey.
2 Press the EDIT COMMENTS.... softkey.
3 Use the navigation keys to enter your comments. See “To enter the ID using the arrow
keys” on page 3-17 and To enter the ID using a trackball or mouse 17 for
information on entering the comment string.
4 When you finish entering the string, click the CONTINUE softkey. The new comment is
displayed on-screen in the Comment field.
NOTE
The new comment is saved only for the current session. Each time a new device is
measured, the comment and ID strings are reset to the values specified in the
specification set.
3-18
Passive Component Test Application
Performing Measurements
To change the default application settings
1 After completing a measurement, press the DOCUMENT RESULTS.... softkey.
2 Press the APPLICATION SETUP.... softkey.
3 Refer to To Fill In a Setup Panel
in the setup panel.
20 for information on changing and selecting items
Setup panel selections Printout Type
The results can be printed out as a graph, a table, or as both.
Printer Location
Selects either the internal printer or an external printer as the print destination.
Save File Type
The data can be saved as either graphical data in CGM format or as tabular
data in CSV.
3-19
Passive Component Test Application
Performing Measurements
To Fill In a Setup Panel
Any of the instrument settings can be changed by using either the front-panel
keys or the menu bar selections. Many of the menu selections and front-panel
keys display a softkey panel. Settings in softkey panels are changed using the
softkeys, data-entry keys, mouse, and trackball.
Setup panels allow you to adjust setup conditions which are not frequently
changed.
Using the softkeys
The arrow softkeys
Allows the user to navigate from field to field in the dialog box. The highlighted
parameter can be changed.
The Select softkey
Selects or deselects the highlighted parameter.
The Defaults softkey
Resets the parameters to their default condition.
Close Panel.... softkey
Saves the current setup and returns the user to the previous menu.
The front-panel number keys, step keys, and knob
Allows the user to enter a numeric value in the highlighted field.
3-20
Passive Component Test Application
Performing Measurements
To use the navigation softkeys
1 Use the arrow softkeys to highlight the settings on the setup panel.
2 Use the SELECT softkey to toggle the selection boxes on and off.
3 Enter values in the numeric fields using the front-panel knob or numeric entry pad.
4 To return the setup values to the instrument’s preset settings, press the DEFAULTS
softkey.
5 When you are satisfied with your selections, press the CLOSE PANEL.... softkey to enter
your selections and close the setup panel.
3-21
Passive Component Test Application
Designing Specification Sets
Designing Specification Sets
What is a specification set?
Specification sets are files that program the Passive Component Test
application to perform a measurement. Each specification set defines one test.
Specification sets are comma-separated-value (CSV) ASCII files that you can
write using any text editor or spreadsheet program. The file name must comply
with the MS-DOS 8.3 file name convention, a maximum of 8 characters, and the
file name extension must be .csv.
How can I write specification sets?
You can use any ASCII editor to create your specification sets. Refer to “Using
an ASCII Editor” on page 3-43 for more information.
You can also simplify the writing of specification sets by using an Excel
template. Refer to “Excel Template Wizard for the PCT Application” on
page 3-23 for more information.
If you use a spreadsheet program to develop your specification sets, configure
the spreadsheet to automatically insert the commas for you when you save
your file.
To learn the details about each specification set keyword, refer to
“Specification Set Keywords” on page 3-57.
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Excel Template Wizard for the PCT Application
Writing specification sets can be simplified by using the Microsoft® Excel
template. The Excel template wizard can be downloaded from the web at
http://www.agilent.com. In the Quick Search box, type “pct wizard”. Click on
“Agilent 86140A Series OSA Passive Component Test Application and then
click on “Download pct wizard.exe”. The template features a pull-down menu
and setup wizard to automate the generation of specification sets.
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Installing the PCT Wizard
The Microsoft® Excel spreadsheet wizard, pct_wizard.xlt, contains a powerful
macro that prompts you for measurement statements and builds a valid
specification set file for your measurement.
Before using the template for the first time, make a backup copy and store it in
a safe place. When working with the template in Excel, use the SAVE CSV button
to prevent writing over the original, unmodified template. To prevent modifying
the original template, on the File menu do not select Save.
To download and install the wizard
The PCT Wizard download is for Microsoft Windows systems only. To
download the PCT Wizard:
1 Create a folder c:\osa\pct\ on your local PC.
2 On the web, go to http://www.agilent.com/comms/osa then click on:
Agilent 86140B Benchtop Standard Performance Optical Spectrum Analyzer
Application Notes and Technical Papers
Passive Component Test Application
Passive Component Test Application
pct_wizard.exe.
3 Download and save the pct_wizard.exe to the c:\osa\pct directory. This is a self
extracting archive.
4 To extract the files, from Windows Explorer, double-click on pct_wizard.exe.
Four files are extracted:
Table 1
readme.txt
A text file of the instructions shown on this web page.
pct_wizard.xlt
The Excel Wizard used to write specification sets.
pct_wizard.dll
The driver file required to run the PCT Wizard.
pct_help.pdf
Instructions for using the PCT Wizard and a brief tutorial. This file can
be viewed and printed using Adobe Acrobat. If you do not have Adobe
Acrobat Reader necessary for viewing PDF documentation, download
your free Acrobat Reader now. (Button)
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Designing Specification Sets
5 Move the pct_wizard.dll to the c:\windows\system directory.
6 Make a backup copy of pct_wizard.xlt and store it in a safe place.
To view the help file
NOTE
You must have Adobe Acrobat reader installed.
• To view the help file and tutorial, from Windows Explorer, double click on pct_help.pdf.
To start the PCT Wizard
NOTE
You must have Microsoft Excel installed.
• To open Excel and start the Wizard, from Windows Explorer, double-click on
pct_wizard.xlt.
NOTE
Never save your work from the file menu. This creates a modified template file which
generates an improper specification set (CSV) file that will not run in the Passive
Component Test application. Always click the SAVE CSV button to save your
specification set.
To remove the PCT Wizard from your PC
1 To remove all files and the PCT Wizard from your PC, delete the folder c:\osa\pct and
all its contents.
2 Delete the file pct_wizard.dll from the c:\windows\system directory.
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The PCT Wizard at a Glance
Begin writing a new specification set
Save the current specification set
Open an existing specification set
Check the syntax of the specification
APPLICATION statement line
with measurement description
Apply color to the specification set
Clear the specification set
Device Information area
Measurement Setup area
Device Measurement area
Results Documentation
The spreadsheet template
Device Information area
This section is used to enter information about the device, such as the
identification and comments. The ID and COMMENT statements allow you to
specify the device you are testing and to label the test. Both of these values
will be shown on the instrument screen. Each time a device is tested, the user
can be prompted to enter the device’s serial number.
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Designing Specification Sets
Measurement Setup area
This section is used to enter measurement setup information, such as the
resolution, span, center wavelength and sensitivity. This area will contain the
required NORMALIZE and SETUP keywords and the optional STIMULUS
keyword to set up the optical spectrum analyzer for measurement.
The SETUP statement configures the settings of the optical spectrum analyzer.
Only one SETUP statement should be used. The NORMALIZE keyword
performs a trace normalization. The STIMULUS statement is used to specify
the internal or external broadband light source of the instrument.
Device Measurement area
This section is used to enter the test sequence and specification limits, such
as, center wavelength and insertion loss. This area of the spreadsheet will
contain the required PATH keyword, and the keywords and parameters for the
chosen measurements.
For a full list of keywords and parameters, refer to “Specification Set
Keywords” on page 3-57.
Results Documentation area
Use this area to specify where and how the measurement results are stored
and printed.
Use PRINT_SETUP to determine whether the summary is printed to the
internal or external printer, and whether to print the results table or both the
table and the graphics.
STORE_SETUP is used to determine what results information is saved to the
floppy disk.
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Designing Specification Sets
To begin the specification set
Every specification set begins with a required APPLICATION statement which
identifies the specification set with the Passive Component Test application. It
also provides an identification string which is displayed when the file is
cataloged. You must edit this string manually in cell C4.
NOTE
Do not modify or delete title rows, such as the “Device Information” row. If these rows
are deleted, the PCT Wizard will not run properly.
After entering the identification string, you can create the specification set
using the PCT Automation wizard.
All specification sets also require entries for SETUP, NORMALIZE, and PATH
keywords. A default path is created whenever the CLEAR SHEET button is
pressed. These will be entered using the wizard. Other keywords are optional.
For a full list of keywords and parameters, refer to “Specification Set
Keywords” on page 3-57.
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To Use the PCT Wizard
1 Click the START button to display the PCT Automation dialog box.
Click to select type of statement to enter
Drop-down list of available statements
Delete last
PCT Automation dialog box
2 There are four types of specification set statements: Device Information,
Measurement Setup, Device Measurement, and Results Documentation. For a
complete description of these statements refer to Filling in the Device Information
area 32, Filling in the Measurement Setup area 35, Filling in the Device
Measurement area 37, Filling in the Results Documentation area 39,
Specification Set Keywords 57.
For each type of specification set statement, click the radio button next to the
statement in the dialog box, then use the menu at the right to select a keyword.
Enter the required information, then click OK to go on to the next item or to
return to the first dialog box.
The UNDO LAST INSERT button allows you to delete the last entry made. If you
need to modify any other entry, close the wizard and then edit the spreadsheet
cell directly.
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Specify measurement value is reported in
Select statement from drop-down list
Description of highlighted
3 When finished, click the EXIT button to close the PCT Automation dialog box. Any
modifications necessary to the spreadsheet entries may be made directly to the
spreadsheet cells after the dialog box is closed.
4 To save the specification set, click the SAVE CVS button. On the File menu, do not
select the Save command. If you do the specification set will not be saved properly.
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Name of specification set listed in the
“Load Spec Set” file listing of the
Passive Component Test application
Required statement identifying
application to run specification
One of two optional statements
for identifying the device being
Required NORMALIZE and
SETUP statements
Instructions for performing
measurements
Variable name for measured
value listed in the measurement
Measurement results sent to the
internal printer
Example of a specification set
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Tutorial
In this tutorial you will create a specification set for measuring the peak
wavelength of a WDM filter. The passband of the filter is from 1540 nm to 1560
nm.
To start the PCT Wizard
1 To open Excel and start the Wizard, from Windows Explorer, double-click on
pct_wizard.xlt.
2 Click the START button.
Filling in the Device Information area
1 In the PCT Automation dialog box, click on the drop-down list and select COMMENT.
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2 In the Comments dialog box text box, type PCT Test Program and then click OK.
3 In the Enter Additional Text During Test? dialog box select the None option button
and then click OK.
4 In the PCT Automation dialog box on the drop-down list select ID.
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5 In the Serial Number dialog box text box type, HB001 and click OK.
6 In the Enter Additional Text During Test? dialog box, click OK to select the default text.
NOTE
The default text of “ENTER” will cause the optical spectrum analyzer to prompt the user
to input a device ID number
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Filling in the Measurement Setup area
To enter the normalize information
1 In the PCT Automation dialog box, select the Measurement Setup option button.
2 In the PCT Automation dialog box select NORMALIZE on the drop-down list.
3 In the Minimum Power Range dialog box enter -40 in the text box. Click OK.
4 In the Maximum Power Range dialog box enter 0 in the text box. Click OK.
5 To set the time between normalizations to two hours, in the Interval between
normalizations dialog box enter 2. Click OK.
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To enter the setup information
1 In the PCT Automation dialog box, select SETUP on the drop-down list.
2 In the Start Wavelength dialog box, type 1540. Click OK.
3 In the Stop Wavelength dialog box, type 1560. Click OK.
4 In the Trace Points dialog box, type 1001. Click OK.
5 In the Averages dialog box, type 1. Click OK.
6 In the Resolution Bandwidth dialog box select the 0.1 nm option button. Click OK.
7 In the Reference Level dialog box, type 0. Click OK.
8 In the Scale (dB per division - optional) dialog box, type 10. Click OK.
9 In the Sensitivity dialog box type, -85. Click OK.
10 In the Video Bandwidth (3kHz max…) dialog box click OK to keep the DEFAULT text.
11 In the PCT Automation dialog box select STIMULUS on the drop-down list.
12 In the Stimulus dialog box click OK to keep the INTERNAL_BBLS text.
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Filling in the Device Measurement area
1 In the PCT Automation dialog box select the Device Measurement option button.
2 In the PCT Automation dialog box select PEAK_WAVELENGTH from the drop-down
list.
NOTE
Use the front-panel up and down arrow keys to cycle through the list of keywords and
display a description of the highlighted keyword.
3 In the Name dialog box type Pk_Wl. Click OK.
NOTE
The name you just entered, Pk_Wl, is now a variable name you can reference later.
4 In the Minimum Spec dialog box, type 1545. Make sure the nm option button is
selected. Click OK.
5 In the Maximum Spec dialog box, type 1555. Click OK.
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6 In the Search From dialog box, type 1540. Click OK.
7 In the Search To dialog box, type 1560.Click OK.
8 In the PCT Automation dialog box select BANDWIDTH_WAVELENGTH on the dropdown list.
9 In the Name dialog box type BW_3dB. Click OK.
NOTE
The name you just entered, BW_3dB, is now a variable name you can reference later.
10 In the Minimum Spec dialog box type 0.1. Click OK.
11 In the Maximum Spec dialog box type 2. Click OK.
12 In the Reference Point dialog box type, Pk_Wl. Select the Name option button. Click
OK .
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NOTE
This command uses the variable Pk_Wl you defined in Step 3 as its reference point. For
this reason it is necessary to click on the Name bullet and not the nm option button. If
an actual known wavelength value is entered, leave the nm option button selected.
13 In the Excursion dialog box, type -3. Click OK.
Filling in the Results Documentation area
1 In the PCT Automation dialog box select the Results Documentation option button.
2 In the PCT Automation dialog box select PRINT_SETUP from the drop-down list.
3 In the Printout Style dialog box select the GRAPHICS_AND_TABLE option button.
Click Ok.
4 In the Printer dialog box click OK to select the default text, INTERNAL.
5 In the PCT Automation dialog box select PRINT on the drop-down list.
6 In the PCT Automation dialog box, click on the Exit button
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Saving your specification set
1 Use the slide bar to go to the top of the template. Click on the SAVE CSV button.
CAUTION
Always click the SAVE CSV button to save your specification set. If you save
your work from the File menu an Excel spreadsheet file ( *.xls) will be saved.
Although you can modify or change this spreadsheet file in the future.an Excel
spreadsheet file will not run in the Passive Component Test application. To
create a file that will run in the Passive Component Test application click on the
SAVE CSV button.
2 Enter the file name and directory of your choice. Note that to port the specification
set to the OSA it must be saved on a floppy disk in the root directory.
CAUTION
When you close the PCT template, Excel will ask you “Do you want to save the
changes you made to 'PCT Template, v1.11'?” Always answer “NO” to this question.
If you answer “YES” the original PCT Template will be changed. If you want to save your work as
an Excel spreadsheet template enter a new filename, such as my_test.xls.
A picture of the completed specification sheet is shown on the following page.
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Passive Component Test Application
Export Spec Set
Export Spec Set
Displays a list of internally stored specification sets. Use the navigation keys to
select the desired specification set and then press the Export Set softkey. The
comma-separated-value (CSV) specification set file from internal memory is
output to the floppy disk.
Key Path
Appl’s > Passive Components > Spec Set DEFAULT > Export Spec Set
Related Functions
Load Spec Set, Import Spec Set, Delete Spec Set
Remote Commands
MMEMory:SSET:DATA?<file_name>
Import New Spec Set
Imports a specification set <file_name>, where <data_block> is a definite
length block containing the specification set. Refer to the Agilent 86140B
Series Measurement Applications User’s Guide (Part Number: 86140-90083)
Key Path
Appl’s >Passive Components > Spec Set Default > Import New Spec Set
Related Functions
Load Spec Set, Export Spec Set, Delete Spec Set
Remote Commands
MMEMory:SSET:DATA <file_name>,<data_block>
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Passive Component Test Application
Load Spec Set
Load Spec Set
Loads an imported specification set as the current set of specs.
Key Path
Appl’s > Passive Components > Load Spec Set
Related Functions
Import New Spec Set, Export Spec Set, Delete Spec Set
Remote Commands
MMEMory:SSET:LOAD<file_name>
MMEMory:SSET:LOAD?
Using an ASCII Editor
There are four types of specification set keywords: System Commands,
Measurement Setup, Device Measurement, and Results Documentation. All
specification sets require the APPLICATION, SETUP, NORMALIZE, and PATH
keywords.
Every specification set begins with the APPLICATION keyword which identifies
the specification set with the Passive Component Test application. It also
provides a label that will be displayed when the specifications set is cataloged
by the Passive Component Test application. Try to make the label descriptive of
the test or device that you are measuring.
After the APPLICATION keyword, use the optional ID and COMMENT keywords
to label the test and device being tested. The entered strings appear on the
instrument’s display as shown in Example 3-2. Add the STIMULUS keyword to
select the broadband light source. Next, use the SETUP and NORMALIZE
keywords to configure the instrument’s settings and perform a trace
normalization, see Example 5-4 on page 3-49.
Follow the PATH keyword with any keywords that are required for your
measurement, followed by keywords to print or store the measurement results.
Only one SETUP keyword should be used. If additional SETUP keywords are
included, only the last keyword is used. Use the SWEEP and ZOOM commands
to sweep a subset of the wavelength range and zoom to the screen.
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Example 3-2.
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Keywords, such as PEAK_WAVELENGTH for example, must use all uppercase
letters. Comments are preceded by a semicolon (;) character. Everything after a
semicolon on a line is ignored. You can also insert blank lines to make your files
easier to read. Keywords can be separated by either spaces or a comma (,)
character. Notice that no flow control keywords, such as branching or looping,
are provided.
Measurement paths require a PATH keyword
Include the PATH keyword before any group of measurement keywords listed
for a specific measurement path. Devices with multiple paths, such as WDM
multiplexers, require one PATH keyword for each path. Example 5-4 on
page 3-49 has one PATH keyword. Example 3-3 on page 3-46 has two PATH
keywords, one for device loss and one for device isolation. All measurement
keywords between two PATH keywords apply to the first PATH keyword. Each
PATH is measured in the order listed in the specification file. The name specified
for each PATH appears in the final result table and on the MEASURE softkey.
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Example 3-3.
Notice the use of the INSTRUCTION keyword to convey instructions to the
user. Each PATH can have one or more INSTRUCTION keywords. The dialog
boxes are displayed in the order of the INSTRUCTION keywords. If no
INSTRUCTION keyword is given for a particular PATH, a default instruction
prompt is displayed. The measurement pauses until the CONTINUE softkey is
clicked. In the displayed string, use the escape sequence \n to enter a newline
character and force a line break.
Pressing the MEASURE DUT softkey brings up an instruction panel.
When the measurement is complete, the results can be viewed both
graphically and in table form, as shown in Figure 4 and Figure 5.
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Figure 4 Measurement results displayed graphically.
Figure 5 Measurement results displayed in tabular format.
Use variables to identify measured values
The first parameter for most measurement keywords is a variable name.
Variables are automatically initialized and allocated the first time that they are
assigned a value by the application. Variables “hold” the measured value for
the keyword. Variable values and names are displayed in the measurement
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results table. To prevent a variable from being displayed in the measurement
results table, begin the corresponding keyword line with a pound sign (#)
character.
The following PEAK_WAVELENGTH keyword defines the variable
PEAK_WAVELENGTH. Notice that the MARKER_LEVEL keyword uses
PEAK_WAVELENGTH, which is measured in the previous step, to define the
wavelength for placing the marker.
PEAK_WAVELENGTH,Peak_wavelength,1545 nm,1555 nm,DEFAULT,DEFAULT
MARKER_LEVEL,Peak_power,-3 dB,3 dB,Peak_wavelength
Variable names can include both upper and lowercase letters but cannot
include spaces; use the underscore character (_) instead. The first character of
a variable must be a letter. Only the first 32 characters of the variable name are
significant. For names to be considered different, the first 32 characters must
not be identical.
Results documentation area
Use this area to specify where and how the measurement results are stored
and printed.
Use PRINT_SETUP to determine whether the summary is printed to the
internal or external printer and whether to print the results table or both the
table and graphics.
STORE_SETUP is used in a similar way to determine what results information
is saved to the floppy disk.
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Example 5-4. Specification set for characterizing a WDM filter.
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Example 5-4 on page 3-49 shows a specification set written to characterize a
WDM filter. The specification set measures the insertion loss, the 3 dB, 6 dB,
and 10 dB bandwidths, the peak wavelength and the crosstalk.
Figure 6 shows the results summary table for a device measured using the
specification set shown in Example 5-4. The device passes the specifications in
this example.
Figure 6 Results summary table for a WDM filter.
Example 6-5 on page 3-51 shows a specification set for characterizing an
optical isolator. Note that it uses two paths, one for the insertion loss and one
for the isolation.
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Example 6-5. Specification set for characterizing an optical isolator.
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Figure 7 shows an example of the results summary table for an optical isolator
characterized using the specification set shown in Example 6-5.
Figure 7 Measurement summary table for an isolator
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Specification Set Flowchart
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Quick List of Keywords
Table 6 List of Keywords (1 of 3)
Command
Description
SYSTEM COMMANDS
APPLICATION, COMPONENTS
Designates the specification set for use with the Passive Component Test
application. Also identifies test in catalog.
COMMENT
Prints comment in comment section of the instrument’s display.
ID
Prints an identification string in ID section of the instrument’s display.
MEASUREMENT SETUP COMMANDS
NORMALIZE
Specifies the minimum and maximum peak power range (in dBm) for the reference
signal for a valid normalization.
SETUP
Configures the optical spectrum analyzer settings.
STIMULUS
Specifies the source that is used to take a reference trace as well as the actual
measurement.
MEASUREMENT COMMANDS
ABS_FREQUENCY_LEFT
Measures the absolute frequency of a trace point.
ABS_FREQUENCY_RIGHT
Measures the absolute frequency of a trace point.
ABS_WAVELENGTH_LEFT
Measures the absolute wavelength of a trace point.
ABS_WAVELENGTH_RIGHT
Measures the absolute wavelength of a trace point.
BANDWIDTH_FREQUENCY
Calculates the bandwidth (in THz).
BANDWIDTH_WAVELENGTH
Calculates the bandwidth (in nm).
CENTER_FREQUENCY
Locates the center frequency (THz).
CENTER_OF_MASS_FREQUENCY
Calculates the mean frequency (THz) representing the center of mass.
CENTER_OF_MASS_WAVELENGTH
Calculates the mean wavelength (nm) representing the center of mass.
CENTER_WAVELENGTH
Locates the center wavelength (nm).
DELTA_FREQUENCY_LEFT
Determines the frequency separation between a measurement point and reference
point.
DELTA_FREQUENCY_RIGHT
Determines the frequency separation between a measurement point and reference
point.
DELTA_WAVELENGTH_LEFT
Determines the wavelength separation between a measurement point and
reference point.
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Table 6 List of Keywords (2 of 3)
Command
Description
DELTA_WAVELENGTH_RIGHT
Determines the wavelength separation between a measurement point and
reference point.
INSTRUCTION
Displays a prompt for the user for a measurement path.
LIN_ADD
Calculates the sum of two, or more, linear power, wavelength, frequency, or
constant values.
LIN_AVG
Calculates the average of two or more values.
LIN_DIV
Calculates the ratio of two, or more, linear power, wavelength, frequency, or
constant values.
LIN_MUL
Calculates the product of two, or more, linear power, wavelength, frequency, or
constant values.
LIN_SUB
Calculates the difference between two, or more, linear power, wavelength,
frequency, or constant values.
LOG_ADD
Calculates the sum of two, or more, logarithmic power, wavelength, frequency, or
constant values.
LOG_SUB
Calculates the difference between two, or more, logarithmic power, wavelength,
frequency, or constant values.
MARKER_LEVEL
Measures the power at the location specified.
MARKER_LOSS
Measures the power loss at the location specified referenced to the normalized
response.
MAX
Calculates the maximum of two or more values.
MIN
Calculates the minimum of two or more values.
PATH
Specifies which set of measurement keywords should be grouped together and
performed on the same trace measurement.
PEAK_FREQUENCY
Measures the frequency (THz) of the maximum power trace point in a wavelength
range.
PEAK_WAVELENGTH
Measures the wavelength (nm) of the maximum power trace point in a wavelength
range.
PIT_FREQUENCY
Measures the frequency (THz) of the minimum power trace point in a wavelength
range.
PIT_WAVELENGTH
Measures the wavelength (nm) of the minimum power trace point in a wavelength
range.
SWEEP
Specifies that the following data should be taken from a partial sweep.
ZOOM
Display the trace over the specified wavelength range on the screen.
RESULTS COMMANDS
PRINT
Prints the measurement results with the settings defined in the PRINT_SETUP
keyword.
PRINT_SETUP
Configures the hardcopy output of the measurement results.
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Table 6 List of Keywords (3 of 3)
Command
Description
PRINT_SUMMARY
Prints the final summary of the results.
STORE,AUTO
Saves the measurement results as defined by the STORE_SETUP keyword.
STORE_SETUP
Configures the output of the measurement results that is stored on a disk in the
front-panel disk drive.
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Specification Set Keywords
Table 7
Convention
Description
<>
Angle brackets indicate text strings entered by the developer.
[]
Square brackets indicate that the keyword DEFAULT can be used instead
of a value or a variable for that parameter. Refer to the actual command
description for the behavior when the DEFAULT keyword is used for a
parameter.
|
Indicates a choice of one element from a list.
{}
Braces indicate a group of constants to select from. Each constant is
separated by the | character.
name
Indicates the variable for which you provide a descriptive name. Any letter
(Aa-Zz) followed by letters, digits (0-9) and underscore (_). Only the first 32
characters are significant.
spec_min
–infinity. The parameter spec_min cannot be a variable, only a constant or
DEFAULT.
spec_max
+infinity. The parameter spec_max cannot be a variable, only a constant or
DEFAULT.
from
Start wavelength or frequency of trace in nm (default) or THz.
to
Stop wavelength or frequency of trace in nm (default) or THz.
excursion
+excursion: means excursion dBs up (for example, from a pit).
-excursion: means excursion dBs down (for example, from a peak).
ref_pt
The reference point to be used for a measurement keyword.
ABS_FREQUENCY_LEFT, name, [spec_min], [spec_max], ref_pt, [excursion]
Measures the absolute frequency of a trace point and loads the value into the
name variable. The value returned by this function is in THz. The point is located
excursion dB away from the amplitude of the reference point (ref_pt). The search
is made on frequencies higher than the reference. Arguments are spec_min and
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spec_max, which are absolute frequency values, or
DEFAULT. The ref_pt can be a
constant or a variable. To return the relative frequency, refer to the DELTA
keywords. If no point on the trace meets the excursion criterion, the keyword is
considered to have failed, and the left endpoint (highest frequency) of the trace
is returned.
ABS_FREQUENCY_RIGHT, name, [spec_min], [spec_max], ref_pt, [excursion]
Measures the absolute frequency of a trace point and loads the value into the
name variable. The value returned by this function is in THz. The point is located
excursion dB away from the amplitude of the reference point (ref_pt). The search
is made on frequencies lower than the reference. Arguments spec_min and
spec_max are absolute frequency values or DEFAULT. The ref_pt can be a
constant or a variable. To return the relative frequency, refer to the DELTA
keywords. If no point on the trace meets the excursion criterion, the keyword is
considered to have failed, and the right endpoint (lowest frequency) of the
trace is returned.
ABS_WAVELENGTH_LEFT, name, [spec_min], [spec_max], ref_pt, [excursion]
Measures the absolute wavelength of a trace point and loads the value into the
name variable. The value returned by this function is in nm. The point is located
excursion dB away from the amplitude of the reference point (ref_pt). The search
is made on wavelengths shorter than the reference. Arguments spec_min and
spec_max are absolute wavelength values or DEFAULT. The ref_pt can be a
constant or a variable. To return the relative wavelength, refer to the DELTA
keywords. If no point on the trace meets the excursion criterion, the keyword is
considered to have failed, and the left endpoint (shortest wavelength) of the
trace is returned.
ABS_WAVELENGTH_RIGHT, name, [spec_min], [spec_max], ref_pt, [excursion]
Measures the absolute wavelength of a trace point and loads the value into the
name variable. The value returned by this function is in nm. The point is located
excursion dB away from the amplitude of the reference point (ref_pt). The search
is made on wavelengths longer than the reference. Arguments spec_min and
spec_max are absolute wavelength values or DEFAULT. The ref_pt can be a
constant or a variable. To return the relative wavelength, refer to the DELTA
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Passive Component Test Application
Load Spec Set
keywords. If no point on the trace meets the excursion criterion, the keyword is
considered to have failed, and the right endpoint (longest wavelength) of the
trace is returned.
APPLICATION, COMPONENTS, “label string”
Designates the specification set for use with the Passive Component Test
application. This keyword must be the first keyword in the specification set.
The label string is used as a description when cataloging the imported
specification sets in the instrument.
BANDWIDTH_FREQUENCY, name, [spec_min], [spec_max], ref_pt, [excursion]
Calculates the bandwidth (in THz) and loads the value into the name variable.
The value returned by this function is in THz. The bandwidth is determined
excursion dB to the left and to the right of the reference point. Negative
excursion values specify a lower amplitude from the reference point, and
positive excursion values specify a higher amplitude. If either the left or right
trace point fails to meet the excursion criterion, the keyword is considered to
have failed. If the left trace point fails, the left endpoint is used for the
bandwidth calculation. If the right trace point fails, the right endpoint is used
for the bandwidth calculation.
BANDWIDTH_WAVELENGTH, name, [spec_min], [spec_max], ref_pt, [excursion]
Calculates the bandwidth (in nm) and loads the value into the name variable.
The value returned by this function is in nm. The bandwidth is determined
excursion dB to the left and to the right of the reference point. Negative
excursion values specify a lower amplitude from the reference point, and
positive excursion values specify a higher amplitude. If either the left or right
trace point fails to meet the excursion criterion, the keyword is considered to
have failed. If the left trace point fails, the left endpoint is used for the
bandwidth calculation. If the right trace point fails, the right endpoint is used
for the bandwidth calculation.
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Passive Component Test Application
Load Spec Set
CENTER_FREQUENCY, name, [spec_min], [spec_max], ref, [excursion]
Locates the center frequency (THz) and loads the value into the name variable.
The value returned by this function is in THz. It represents the mean value of
the two frequencies found excursion dB down (for negative excursion value) or
up (for positive excursion value) to the left and right of the reference point. The
reference parameter can be a variable or a constant. If either the left or right
trace point fails to meet the excursion criterion, the keyword is considered to
have failed. If the left trace point fails, the left endpoint is used for the
bandwidth calculation. If the right trace point fails, the right endpoint is used
for the bandwidth calculation.
CENTER_OF_MASS_FREQUENCY, name, [spec_min], [spec_max], [from], [to]
Calculates the mean frequency (THz) and loads the value into the name variable.
The value returned by this function is in THz. The mean value represents the
center of mass of the trace over the range from–to.
CENTER_OF_MASS_WAVELENGTH, name, [spec_min], [spec_max], [from], [to]
Calculates the mean wavelength (nm) and loads the value into the name
variable. The value returned by this function is in nm. The mean value
represents the center of mass of the trace over the range from–to.
CENTER_WAVELENGTH, name, [spec_min], [spec_max], ref, [excursion]
Locates the center wavelength (nm) and loads the value into the name variable.
The value returned by this function is in nm. It represents the mean value of the
two wavelengths found excursion dB down (for negative excursion value) or up
(for positive excursion value) to the left and right of the reference point. The
reference parameter can be a variable or a constant. If either the left or right
trace point fails to meet the excursion criterion, the keyword is considered to
have failed. If the left trace point fails, the left endpoint is used for the
bandwidth calculation. If the right trace point fails, the right endpoint is used
for the bandwidth calculation.
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Passive Component Test Application
Load Spec Set
COMMENT, “<any text>”, ENTER
Allows the application user to enter a comment for the device being tested.
The optional ENTER parameter causes a dialog box to appear before the
measurement of the first path, prompting the operator to enter a comment. The
maximum number of characters that can be displayed on the screen is 56.
DELTA_FREQUENCY_LEFT, name, [spec_min], [spec_max], ref_pt, [excursion]
Determines the frequency separation between a measurement point and
reference point and loads the value into the name variable. The value returned
by this function is in THz. The measurement point is located excursion dB away
from the amplitude of the reference point (ref_pt). The search is made on
frequencies higher than the reference. The value of the frequency returned is
positive. Arguments spec_min and spec_max are absolute frequency values or
DEFAULT. The ref_pt can be a constant or a variable. To return the absolute
frequency, refer to the ABS keywords. If no point on the trace meets the
excursion criterion, the keyword is considered to have failed, and the
separation between the left endpoint of the trace and the reference point is
returned.
DELTA_FREQUENCY_RIGHT, name, [spec_min], [spec_max], ref_pt, [excursion]
Determines the frequency separation between a measurement point and
reference point and loads the value into the name variable. The value returned
by this function is in THz. The measurement point is located excursion dB away
from the amplitude of the reference point (ref_pt). The search is made on
frequencies lower than the reference. The value of the frequency returned is
negative. Arguments spec_min and spec_max are absolute frequency values or
DEFAULT. The ref_pt can be a constant or a variable. To return the absolute
frequency, refer to the ABS keywords. If no point on the trace meets the
excursion criterion, the keyword is considered to have failed, and the right
endpoint of the trace is returned.
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Passive Component Test Application
Load Spec Set
DELTA_WAVELENGTH_LEFT, name, [spec_min], [spec_max], ref_pt, [excursion]
Determines the wavelength separation between a measurement point and
reference point and loads the value into the name variable. The value returned
by this function is in nm. The measurement point is located excursion dB away
from the amplitude of the reference point (ref_pt). The search is made on
wavelengths shorter than the reference. The value of the wavelength returned
is negative. Arguments spec_min and spec_max are absolute wavelength values
or DEFAULT. The ref_pt can be a constant or a variable. To return the absolute
wavelength, refer to the ABS keywords. If no point on the trace meets the
excursion criterion, the keyword is considered to have failed, and the left
endpoint of the trace is returned.
DELTA_WAVELENGTH_RIGHT, name, [spec_min], [spec_max], ref_pt, [excursion]
Determines the wavelength separation between a measurement point and
reference point and loads the value into the name variable. The value returned
by this function is in nm. The measurement point is located excursion dB away
from the amplitude of the reference point (ref_pt). The search is made on
wavelengths longer than the reference. The value of the wavelength returned
is positive. Arguments spec_min and spec_max are absolute wavelength values or
DEFAULT. The ref_pt can be a constant or a variable. To return the absolute
wavelength, refer to the ABS keywords. If no point on the trace meets the
excursion criterion, the keyword is considered to have failed, and the left
endpoint of the trace is returned.
ID, “<serial number>”, ENTER
Allows the application user to enter an identification number for the device
being tested. The optional ENTER parameter causes a dialog box to appear
before the measurement of the first path, prompting the operator to enter the
identification number. The ID keyword is not required in a specification set.
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INSTRUCTION, “<prompt string>”
Displays a prompt for the user in a dialog box. Each PATH can have one or more
INSTRUCTION keywords. The dialog boxes are displayed in the order of the
INSTRUCTION keywords. If no INSTRUCTION keyword is given for a particular
PATH, a default instruction prompt is displayed. The measurement pauses until
the CONTINUE softkey is clicked.
Use the escape sequence \n to enter a newline character and force a line
break. Use the escape sequence \” to enter a double quote character.
LIN_ADD, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the sum of two or more linear power, wavelength, frequency, or
constant values. The value returned by this function is in nm, THz, or dB,
depending on the inputs. The sum is loaded into the name variable.
LIN_AVG, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the average of two or more values and loads the value into the name
variable. The values are converted to linear and the linear average is calculated.
LIN_DIV, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the ratio of two or more linear power, wavelength, frequency, or
constant values. The value returned by this function is in nm, THz, dB, or
unitless, depending on the inputs. The ratio is loaded into the name variable.
LIN_MUL name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the product of two or more linear power, wavelength, frequency, or
constant values. The value returned by this function is in nm, GHz, or dB. The
product is loaded into the name variable.
LIN_SUB, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the difference between two or more linear power, wavelength,
frequency, or constant values. The value returned by this function is in nm,
GHz, or dB. The difference is loaded into the name variable.
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Load Spec Set
LOG_ADD, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the sum of two or more logarithmic power, wavelength, frequency,
or constant values. The value returned by this function is in dB. The sum is
loaded into the name variable.
LOG_SUB, name, [spec_min], [spec_max], value1, value2, ... , valueN
Calculates the difference between two or more logarithmic power, wavelength,
frequency, or constant values. The value returned by this function is in dB. The
difference is loaded into the name variable.
MARKER_LEVEL, name, [spec_min], [spec_max], ref_pt
Measures the power at the reference point specified and loads the value into
the name variable. The value returned by this function is in dB. The power (dBm)
or loss (dB) is dependent on the trace at a given wavelength. The ref_pt
parameter can be a wavelength, frequency, or a previously defined name. Log
interpolation of the power level is used if ref_pt doesn’t fall exactly on a trace
point.
MARKER_LOSS, name, [spec_min], [spec_max], ref_pt
Measures the power loss at the reference point specified, and loads the value
into the name variable. Although the marker measures a negative decibel value,
the returned value is positive to represent loss. The ref_pt parameter can be a
wavelength, frequency, or a previously defined name. Log interpolation of the
power level is used if ref_pt doesn’t fall exactly on a trace point.
This keyword is provided as a convenience when measuring values, like
insertion loss, which are typically specified with positive dB values but
measured as negative dB values by the OSA.
MAX, name, [spec_min], [spec_max], value1, value2, .., valueN
Calculates the maximum of two or more values and loads the value into the
name variable. All the values must have the same units. The spec_min and
spec_max parameters must be either DEFAULT or constants with the same units
as the values.
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Load Spec Set
MIN, name, [spec_min], [spec_max], value1, value2,..., valueN
Calculates the minimum of two or more values and loads the value into the
name variable. All the values must have the same units. The spec_min and
spec_max parameters must be either DEFAULT or constants with the same units
as the values.
NORMALIZE, [spec_min], [spec_max], [interval]
Specifies the minimum and maximum peak power range (in dBm) for the
reference signal for a valid normalization. Failures cause the message
“Normalization failed, clean connector and try again” to be displayed. All buttons
except NORMALIZE REFERENCE are disabled. Pushing NORMALIZE REFERENCE starts the
sequence again. Interval specifies the time interval between calibrations in
hours. For example, 0.5h corresponds to 30 minutes. The maximum and
DEFAULT value for the interval is 24 hours.
PATH, name
Specifies which set of measurement keywords should be grouped together and
performed on the same trace measurement. The name specified for each PATH
appears in the final result table and on the MEASURE softkey. For example, a
coupler would require two PATH keywords, one for each arm of the coupler.
Each PATH uses its own trace. All measurement keywords between two PATH
keywords apply to the first PATH keyword. Each PATH is measured in the order
listed in the specification file.
PEAK_FREQUENCY, name, [spec_min], [spec_max], [from], [to]
Measures the frequency (THz) of the maximum power trace point in a
wavelength range. The units returned by this function are in THz. The
measured value is placed in the name variable.
PEAK_WAVELENGTH, name, [spec_min], [spec_max], [from], [to]
Measures the wavelength (nm) of the maximum power trace point in a
wavelength range. The units returned by this function are in nm. The measured
value is placed in the name variable.
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Passive Component Test Application
Load Spec Set
PIT_FREQUENCY, name, [spec_min], [spec_max], [from], [to]
Measures the frequency (THz) of the minimum power trace point in a
wavelength range. The units returned by this function are in THz. The
measured value is placed in the name variable.
PIT_WAVELENGTH, name, [spec_min], [spec_max], [from], [to]
Measures the wavelength (nm) of the minimum power trace point in a
wavelength range. The units returned by this function are in nm. The measured
value is placed in the name variable.
PRINT
Prints the results with the settings defined in the PRINT_SETUP keyword.
PRINT_SETUP, {TABLE | GRAPHICS | GRAPHICS_AND_TABLE}, {INTERNAL | EXTERNAL}
Configures the hardcopy output of the measurement results. Either the
instrument’s internal printer or an external printer can be selected. As shown in
the following table, the type of data printed is also selectable. Although
application users can temporarily override these selections for the current
measurement, when a new device is measured the print setup resets to the
values defined by the PRINT_SETUP keyword.
Table 8
Constant
Description
TABLE
Prints the measurement data in a table.
GRAPHICS
Prints the instrument’s display.
GRAPHICS_AND_TABL
E
Prints the measurement data in a table along with the
instrument’s display.
INTERNAL
Selects the instrument’s internal printer.
EXTERNAL
Selects an external printer.
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Load Spec Set
PRINT_SUMMARY
Prints the final summary of the results.
SETUP, start_wvl, stop_wvl, [pts], [avgs], [rbw], [ref_lvl], [scale], [sens], [vbw]
This required keyword configures the following optical spectrum analyzer
settings:
start wavelength (nm)
stop wavelength (nm)
number of trace points
number of trace averages
resolution bandwidth (nm)
reference level (dBm)
amplitude scale (dB)
sensitivity (dBm)
video bandwidth (Hz)
The following line shows an example of this keyword:
SETUP 1500.00,nm,1600.00,nm,4001,1,0.10,nm,+10.00,dBm,10,dB,90.0,dBm,100,Hz
These settings are always used when performing a normalization. PATH
measurements also use these settings unless changed by the SWEEP
keyword. If a parameter other than avgs is set to DEFAULT, the optical spectrum
analyzer keeps its current setting. For the avgs parameter the DEFAULT keyword
will set the value to 1. Otherwise, the SETUP keyword changes the setting to
whatever is specified for a parameter. This behavior has the potential
consequence of allowing the SWEEP keyword to change the sensitivity from
the first normalization for subsequent normalizations.
For example, suppose that the instrument is currently at –70 dBm sensitivity
and the SETUP keyword has DEFAULT for the sensitivity parameter. There is a
SWEEP keyword with –80 dBm for sensitivity. This results in the first
normalization being performed at –70 dBm sensitivity. After a path is measured
which sets the instrument to –80 dBm sensitivity, subsequent normalizations
will be made at –80 dBm.
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Passive Component Test Application
Load Spec Set
There should be only one SETUP command in a specification set. Multiple
SETUP commands generate a warning when the specification set is imported,
but the specification set can still be imported. The settings of the last SETUP
command will be the ones used by the specification set.
The start and stop wavelength values can only be constants. DEFAULT is not
allowed for these values. All other parameter values must be either constants
with units or the keyword DEFAULT. Variables are not allowed as parameters
for this keyword.
STIMULUS, {INTERNAL_BBLS | EXTERNAL_BBLS}
Specifies the source that is used to take a reference trace, as well as the actual
measurement.
Table 9
Constant
Description
INTERNAL_BBLS
Selects the instrument’s internal white-light or EELED broadband
light source.
EXTERNAL_BBLS
Selects an external unmodulated broadband light source.
STORE, AUTO
Saves the measurement results as defined by the STORE_SETUP keyword. A
filename is automatically generated from the last 8 characters of the
identification string entered using the ID keyword. The only legal characters for
the filename are letters, numbers, and the underscore (_) character. If the ID
string contains any other characters, those characters will be replaced with the
underscore character. If a file already exists on the disk with the same
filename, the file will be overwritten. There is no prompt for overwrite.
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Passive Component Test Application
Load Spec Set
STORE_SETUP, {TABLE | GRAPHICS}
Configures the output of the measurement results that is stored on a disk in the
front-panel disk drive. Although application users can temporarily override
these selections for the current measurement, when a new device is
measured, the storage setup resets to the values defined by the STORE_SETUP
keyword. Use the STORE, AUTO keyword to actually store the data.
Table 10
Constant
Description
TABLE
Stores the measurement data in a table, as well as all of the
traces used for the measurements, in comma-separated-value
(CSV) format.
GRAPHICS
Stores the measurement data in a CGM graphic file.
SWEEP, start_wvl, stop_wvl, [avgs], [sens]
Specifies that the following data should be taken from a partial sweep.
Normalization traces are always made using the conditions specified by
SETUP. You can use this keyword to decrease measurement time by setting the
instrument to sweep over a smaller wavelength range or with different trace
averaging or sensitivity. The wavelength range specified here must fall within
the one given in SETUP. In order to maintain integrity with the reference trace,
the SWEEP function does not change the absolute wavelength position of
trace points nor does it change the hardware reference level.
The start and stop wavelength values can only be constants. DEFAULT is not
allowed for these values. All other parameter values must be either constants
with units or the keyword DEFAULT for the optional parameters. Variables are
not allowed as parameters for this keyword.
ZOOM, start_wvl, stop_wvl, [ref_lvl], [scale]
Displays the trace over the specified wavelength range on the screen. The
zoom is performed after the path measurement is completed. If multiple ZOOM
keywords are used for a PATH, only the last ZOOM keyword is used. Variables
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Load Spec Set
are not allowed as parameters for this keyword. The start and stop wavelength
values can only be constants. DEFAULT is not allowed for these values.
Reference level and scale values must be either constants with units or the
keyword DEFAULT. DEFAULT reference level or the scale parameters specify
that those settings will not change when zooming in the display.
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Passive Component Test Application
Passive Component Test Remote Commands
Passive Component Test Remote Commands
The Agilent 86140B Series Optical Spectrum Analyzer User’s Guide for the
mainframe provides detailed information on remote programming of the
instrument. Only commands unique to the Passive Component Test application
are included in this section.
Passive Component Test application specific commands
These remote commands are specific to the Passive Component Test
application and allow you to control the application remotely. They are grouped
under the following subsystems:
• CALCulate Subsystem Commands
• DISPlay Subsystem Commands
• FORMat Subsystem Commands
• HCOPy Subsystem Commands
• INITiate Subsystem Commands
• MMEMory Subsystem Commands
• SENSe Subsystem Commands
• TRACe Subsystem Commands
For more information, refer to the Remote Operation section in the Agilent
86140B Series Optical Spectrum Analyzer User’s Guide, or to the following
book:
SCPI Consortium. SCPI–Standard Commands for Programming Instruments, 1997
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Passive Component Test Remote Commands
Command Conventions
Table 11
Convention
Description
<>
Angle brackets indicate text strings entered by the developer.
[]
Square brackets indicate that the keyword DEFAULT can be used instead
of a value or a variable for that parameter. Refer to the actual command
description for the behavior when the DEFAULT keyword is used for a
parameter.
|
Indicates a choice of one element from a list.
{}
Braces indicate a group of constants to select from. Each constant is
separated by the | character.
name
Indicates the variable for which you provide a descriptive name. Any letter
(Aa-Zz) followed by letters, digits (0-9) and underscore (_). Only the first 32
characters are significant.
spec_min
–infinity. The parameter spec_min cannot be a variable, only a constant or
DEFAULT.
spec_max
+infinity. The parameter spec_max cannot be a variable, only a constant or
DEFAULT.
from
Start wavelength or frequency of trace in nm (default) or THz.
to
Stop wavelength or frequency of trace in nm (default) or THz.
excursion
+excursion: means excursion dBs up (for example, from a pit).
-excursion: means excursion dBs down (for example, from a peak).
ref_pt
The reference point to be used for a measurement keyword.
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CALCulate Subsystem Commands
The CALCulate subsystem performs post-acquisition data processing. The
CALCulate subsystem operates on data acquired by a SENSe function.
CALCulate:DATA:GRAPh?
Returns the trace plot as an indefinite length block. After removing the #0
prefix and newline suffix, the data can be saved as a cgm format file.
CALCulate:DATA:RESults?
Returns a comma separated list of measurement results. The results are
returned in the order defined by the specification set file. The results are the
same as the results table.
CALCulate:DATA:TABLe?
Returns the measurement data in tabular format as an indefinite length block.
The measurement data contains the table of results, instrument settings, and
trace points. After removing the #0 prefix and newline suffix, the data can be
saved as a csv format file.
CALCulate:PATH[:NAME]?
Returns the name of the device path to be tested as defined in the specification
set.
CALCulate:PATH:RESult?
Returns the result of the device path measurement.
• -1 = No measurement made
• 0 = Device path failed specs
• 1 = Device path passed specs
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Passive Component Test Application
Passive Component Test Remote Commands
CALibration Subsystem Commands
This subsystem has the function of performing system calibration.
CALibration Alignment
Performs an automatic alignment of the instrument at the wavelength of the
largest signal found in full span. This aligns the monochromator output with
the photodetector for improved amplitude accuracy. Sending this command
with a marker on screen will generate a Settings conflict error.
Syntax
CAL:ALIG
Related Key
Auto Align
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Passive Component Test Application
Passive Component Test Remote Commands
DISPlay Subsystem Commands
The DISPlay subsystem controls the selection and presentation of textual,
graphical, and TRACe information.
DISPlay[:WINDow]:DUT:COMMent<string>
Enters a new comment string for the device under test.
DISPlay[:WINDow]:DUT:COMMent?
Returns the comment string for the device under test.
DISPlay[:WINDow]:DUT[:ID]<string>
Enters a new identification string for the device under test.
DISPlay[:WINDow]:DUT[:ID]?
Returns the identification string for the device under test.
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Passive Component Test Remote Commands
FORMat Subsystem Commands
The FORMat subsystem sets a data format for transferring numeric and array
information.
FORMat[:DATA] REAL[64]|ASCII
FORMat[:DATA]?
Specifies the trace data format used during data transfer via GPIB. This
command effects data transfers for the CALCulate[:DATA] subsystem.
The ASCII format is a comma-separated list of numbers.
The REAL format is a definite-length block of 64-bit floating-point binary
numbers. The definite-length block is defined by IEEE 488.2: a “#” character,
followed by one digit (in ASCII) specifying the number of length bytes to follow,
followed by the length (in ASCII), followed by length bytes of binary data. The
binary data is a sequence of 8-byte, 64-bit floating point numbers.
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Passive Component Test Remote Commands
HCOPy Subsystem Commands
The HCOPy subsystem controls the setup of and printing to an external device.
HCOPy:DESTination”SYSTem:COMMunicate:INTernal”|”SYSTem:COMMunicate:
CENTronics”
HCOPy:DESTination?
Selects the I/O port for hardcopy output. This effects subsequent use of the
PRINT key and the HCOPy[:IMMediate] command.
HCOPy:DEVice:MODE TABLe|GRAPh|ALL
Determines the hardcopy output of the measurement results. The data can be
printed as a table, a graph, or both.
HCOPy:IMMediate
Prints out the test results to the port defined by the HCOPy:DESTination
command. The data printed is affected by the HCOPy:DEVice:MODE command.
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Passive Component Test Remote Commands
INITiate Subsystem Commands
The INITiate subsystem is used to control the initiation of the TRIGger
subsystem.
INITiate:IMMediate[:SEQuence [1|2]]
Initiates the normalization routine (sequence 1) or the measurement routine
(sequence 2) based on the sequence number. Measures only one path at a
time.
INITiate:ABORt
Aborts the measurement of a device under test.
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Passive Component Test Application
Passive Component Test Remote Commands
INSTrument Subsystem Commands
The INSTrument subsystem provides a mechanism to identify and select
logical instruments by either name or number. Arguments and responses are
case sensitive.
INSTrument:CATalog?
{OSA,PassiveComponent,WDM_AutoScan<null>}
Comma-separated list of strings representing the Modes and Applications
supported in the instrument.
INSTrument:CATalog:FULL?
{OSA,0,PassiveComponent,1,WDM_AutoScan,2}
Comma-separated list of string-numeric pairs representing the Modes and
Applications supported in the instrument.
INSTrument:SELect <identifier> identifier - string
INSTrument:NSELect <numeric_value>
INSTrument:NSELect?
Loads the application or instrument mode specified.
Example
INSTrument:SELect ”WDM_AutoScan”
INSTrument:NSELect 2
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Passive Component Test Application
Passive Component Test Remote Commands
MMEMory Subsystem Commands
The MMEMory subsystem provides mass storage capabilities for instruments.
The mass storage may be either internal or external to the instrument.
MMEMory:SSET:CATalog?
Returns a comma separated list of imported specification sets from the
instrument’s internal memory.
MMEMory:SSET:DATA<file_name>,<data_block>
MMEMory:SSET:DATA? <file_name>
Imports a specification set <file_name>, where <data_block> is a definite
length block containing the specification set. Refer to “Designing Specification
Sets” on page 3-22 for additional designing information.
Returns a specification set file <file_name> as an indefinite length block. After
removing the #0 prefix and newline suffix, the data can be saved as a csv
format file.
MMEMory:SSET:DELete<file_name>
Deletes a specification set from the instruments internal memory.
MMEMory:SSET:LOAD<file_name>
MMEMory:SSET:LOAD?
Loads an imported specification set as the current set of specs.
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Passive Component Test Remote Commands
SENSe Subsystem Commands
The SENSe setup commands control the specific settings of the device.
[SENSe]:SWEep:POINts?
Returns the number of data points acquired during a sweep. This command is
used in conjunction with the TRACe:POINts? query when downloading a trace.
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Passive Component Test Application
Passive Component Test Remote Commands
TRACe Subsystem Commands
A TRACe area is a named entity stored in instrument memory.
TRACe[:DATA]?TRA|TRB|TRC|TRD|TRE|TRF
Returns the data points for the trace. The trace data format is determined by
the FORMat subsystem.
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Passive Component Test Application
Sample Program
Sample Program
10 ! Program to demonstrate selecting a spec set
20 ! and then reading the results
30 !
40 ! The spec set for this program is example 3-15.
50 !
60 ! re-store “pctbfg”
70 !
80 ASSIGN @Osa TO 723;EOL CHR$(12) END
! Set command terminator to LF
& EOI
90 !
100 PRINTER IS “results.txt”
110 !
120 OUTPUT @Osa;”inst:sel ‘PassiveComponent’”
! Loads PCT application
130 ! Note that a name must be in delimiters, ‘ or “
140 !
150 !
160 OUTPUT @Osa;”mmem:sset:load ‘PASS100’”
! Load spec set from memory
170 !
180 OUTPUT @Osa;”disp:dut:comm ‘Remote measurement control’” ! Send comment line
190 OUTPUT @Osa;”disp:dut:comm?”
200 ENTER @Osa;Comment$
210 PRINT Comment$
220 !
230 OUTPUT @Osa;”disp:dut:id ‘DUT 12678’”
! Send a new DUT ID
240 OUTPUT @Osa;”disp:dut:id?”
250 ENTER @Osa;Id$
260 PRINT Id$
270 !
280 PRINT “Make connections for normalization”
290 INPUT “Ready? Press Enter”,A$
300 OUTPUT @Osa;”init:imm:seq 1”
! Execute normalization routine
310 !
390 !
400 PRINT “Make connections for measurement”
410 INPUT “Ready? Press Enter”,A$
420 OUTPUT @Osa;”init:imm:seq 2”
! Execute measurement routine
430 !
3-83
Passive Component Test Application
Sample Program
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
610
620
630
640
650
660
670
680
700
OUTPUT @Osa;”calc:path:res?”
! Query measurement results
ENTER @Osa;Results
IF Results=1 THEN 500
! Test for 1 as measurement passed
PRINT “Measurement failed “;Results
BEEP
STOP
PRINT “Measurement Passed”
!
! *** Read measurement table results ***
!
OUTPUT @Osa;”calc:data:res?”
! Read results column in table
ENTER @Osa;Peak_wl,Ins_loss,Bwidth_3db,Bwidth_6db,Bwidth_10db,Xtalk
!
PRINT “Peak Wavelength”,Peak_wl
PRINT “Insertion Loss”,Ins_loss
PRINT “3 dB Bandwidth”,Bwidth_3db
PRINT “6 dB Bandwidth”,Bwidth_6db
PRINT “10 dB Bandwidth”,Bwidth_10db
PRINT “Cross talk”,Xtalk
!
! *** Print out table ***
!
OUTPUT @Osa;”hcop:dev:mode tabl”
! Select table for printout
OUTPUT @Osa;”hcop:imm”
! print
!
END
Remote measurement
DUT 12678
Make connections for normalization
Make connections for measurement
Measurement Passed
Peak Wavelength
Insertion Loss
1553.794
8.47
3 dB Bandwidth
.585
6 dB Bandwidth
.703
10 dB Bandwidth
.891
3-84
Passive Component Test Application
Sample Program
Cross talk
21
Model# / Serial#
FW Rev / App Rev
Sens / Measured in
Parameter
Passband
Peak._WL
Insertion_Loss
BandWidth_3dB
BandWidth_6dB
BandWidth_10dB
XTalk
86142A / US38380189
P.03.00
-85.11 dBm / In Vacuum
Actual
1553.794
nm
8.47 dB
0.585 nm
0.703 nm
0.891 nm
21.00 dB
Spec Min
Spec Max
1540.00
1560.00
-0.500
0.500
0.500
12.00
10.00
1.700
1.700
2.00
--
3-85
Passive Component Test Application
Sample Program
3-86
4
About the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
The Measurement Applications Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Performing Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Starting the Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
WDM Channel Analysis Remote Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Command Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
CALCulate Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
CALibration Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
DISPlay Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
FORMat Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
INPut Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
INSTrument Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
ROUTe Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
SENSe Subsystem Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
WDM Channel Analysis Application
WDM Channel Analysis Application
About the Application
About the Application
The WDM channel analysis application gives accurate wavelength, power and
optical signal-to-noise ratio measurements. The results are displayed in an
easy-to-read table. The WDM channel analysis application calculates the
following attributes and display the results in the table:
•
•
•
•
•
•
•
•
•
•
•
Channel number for the channel with the maximum power
Maximum channel power (dBm)
Channel number for the channel with the minimum power
Minimum channel power (dBm)
Channel number for the channel with the maximum optical signal-to-noise ratio
Maximum optical signal-to-noise ratio (dB)
Channel number for the channel with the minimum optical signal-to-noise ratio
Minimum optical signal-to-noise ratio (dB)
Span tilt (dB/nm)
Span tilt (dB)
Peak-to-peak deviation, defined as:
maximum channel power – minimum channel power
Using a noise sweep resolution bandwidth of 0.06 nm, the maximum
wavelength span that can be measured is 75 nm. The maximum number of
WDM channels that can be measured is 187.
The WDM channel analysis application uses a unique dual-sweep
measurement technique. The first sweep uses a slightly broader filter to
accurately measure signal power. The other sweep uses a very narrow band
filter to measure the power density of the noise floor. The noise markers, which
are corrected for filter shape, provide improved accuracy for the noise floor
power density measurement which results in increased measurement
accuracy of the optical signal-to-noise ratio.
This section provides a description of the user interface for this application.
The behavior of the “Applications” menu of the OSA is also described.
4-2
WDM Channel Analysis Application
About the Application
The Measurement Applications Menus
4-3
WDM Channel Analysis Application
About the Application
The application softkeys are accessed using the front-panel APPL’S key or the
Applications menu, Launch an Installed Application selection on the menu bar.
4-4
WDM Channel Analysis Application
Performing Measurements
Performing Measurements
This section provides procedures for performing the following functions:
To start the WDM channel analysis application 4-7
To perform an autoscan 4-8
To set up a measurement 4-9
To start a measurement 4-14
To stop a measurement 4-14
To display the results in a table 4-16
To change the wavelength units in the table 4-18
To document measurement results 4-19
To save the results to floppy 4-20
To print the results 4-21
To enter a device ID 4-22
To enter comments 4-23
To set up the printer 4-24
To exit the application 4-24
Note
The following functions assume the lightwave component analyzer is loaded.
4-5
WDM Channel Analysis Application
Performing Measurements
Starting the Application
This section explains how to start and use the WDM channel analysis
application.
With the WDM channel analysis application you can test WDM sources, WDM
multiplexers and other WDM components, such as filters and couplers.
To use the WDM channel analysis application you must:
1 Start the application, refer to “To start the WDM channel analysis application” on
page 4-7.
2 Set up the measurement, refer to “To set up a measurement” on page 4-9.
3 Measure the device under test.
You can then:
• View the results in a table, refer to “To display the results in a table” on page 4-16.
• Save the results, refer to “To save the results to floppy” on page 4-20.
• Print the results, refer to “To print the results” on page 4-21.
4 Examine one channel or wavelength range in filter mode.
4-6
WDM Channel Analysis Application
Performing Measurements
To start the WDM channel analysis application
1 Press the front-panel APPL’S key or on the Applications menu select Launch an
Installed Application.
2 The following screen is displayed.
Figure 1 Applications Panel and Menu
The panel and the menu change whenever an application is installed or uninstalled. Each installed application has an icon on the panel and a
corresponding softkey.
3 Press the WDM SPECTRUM softkey to launch the channel analysis application.
4-7
WDM Channel Analysis Application
Performing Measurements
To perform an autoscan
Press the START AUTOSCAN.... softkey.
An automated channel scan is performed. The channel power, wavelength,
optical signal-to-noise ratio, spectral gain tilt, and other statistics can be
displayed either graphically or in a tabular format.
4-8
WDM Channel Analysis Application
Performing Measurements
To set up a measurement
Press the MEASUREMENT SETUP... softkey to open the Measurement setup menu
and panel. This softkey is enabled whenever the system is not actively
measuring.
The Measurement Setup panel opens.
4-9
WDM Channel Analysis Application
Performing Measurements
WDM Measurement Setup panel
Setup panel selections Start Wavelength
Default: 1530 nm
Sets the start wavelength for the Auto Scan function. Units are fixed in nm.
Stop Wavelength
Default: 1570 nm
Sets the stop wavelength for the Auto Scan function. Units are fixed in nm.
Wavelength Units
Default: nm
Selects the wavelength units, either nm or THz. These units are used in the
display table only.
Peak Excursion
Default: 10 dB
4-10
WDM Channel Analysis Application
Performing Measurements
Sets the peak excursion value in dB. This is the amount of amplitude the trace
must rise and fall to considered a peak. Lower values lead to more signals
being discerned, but if the peak excursion is set too low, peaks in the noise
floor may be discerned as signals. If excursion is set too high, legitimate peaks
may not be discerned as signals.
Peak Threshold
Default: -55 dBm
Sets the peak threshold value in dBm. Power levels below this threshold are
not considered for peak search.
Noise Method
Default: Pit
Selects the noise method used: You can choose BETWEEN CHANNELS, PIT, or
OFFSET.
When Between Channels is selected, the Noise marker is placed half-way
between channels when making a noise power density measurement. The
Noise power density used in the OSNR calculation is linearly interpolated
between the noise marker to the left and to the right of the channel. If the
channel is the leftmost or rightmost channel in the measurement range, the
noise would then be measured using the offset value for the side without an
adjacent channel.
When Pit is selected, the noise marker is placed at the lowest point between
adjacent channels. The Noise power density used in the OSNR calculation is
linearly interpolated between the noise marker to the left and to the right of the
channel. If a pit is not detected for the left and right side, the offset value
specified for the noise measurement is used.
When Offset is selected, the noise marker ‘noise offset’ is placed to the left and
to the right of the channel when making a noise power density measurement.
The Noise power density used in the OSNR calculation is linearly interpolated
between the noise marker to the left and to the right of the channel. The noise
is always measured at the offset value specified.
4-11
WDM Channel Analysis Application
Performing Measurements
Channel Spacing
Default: 100 GHz
Sets the channel spacing value in GHz. This value is the spacing between
adjacent channels on the input signal. This value is used to calculate the noise
offset value to use (noise offset = 1/2 channel spacing). The calculated noise
offset value is displayed to the right of the channel spacing.
Sensitivity
Default: –65 dBm
Sets31 the sensitivity value in dBm. Increasing sensitivity results in a more
precise scan but increases the scan time.
Peak Sweep Res BW
Default: 0.2 nm
Sets the resolution bandwidth value to be used during peak sweep. This
determines the analyzer’s ability to display two closely spaced signals as two
distinct responses. Decreasing the resolution bandwidth provides a more
detailed sweep but increases the scan time. The resolution bandwidth can be
set to one of the following values: 0.07, 0.09, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9,
or 10 nm. For model 86142B, the minimum setting is 0.06 nm.
Noise Sweep Res BW
Default: 0.1 nm
Sets the resolution bandwidth value to use during noise sweep. This
determines the analyzer’s ability to display two closely spaced signals as two
distinct responses. Decreasing the resolution bandwidth provides a more
detailed sweep but increases the scan time. The resolution bandwidth can be
set to one of the following values: 0.06, 0.09, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9,
or 10 nm. For model 86141B and 86140B Option 025, the minimum setting is
0.07 nm.
Measurement Trigger Mode
Default: Single Trigger mode
4-12
WDM Channel Analysis Application
Performing Measurements
Select either single or continuous trigger mode.
The navigation key operation is explained in To fill in a setup panel 25.
4-13
WDM Channel Analysis Application
Performing Measurements
To start a measurement
• Press the START AUTOSCAN softkey to start the measurement process.
A 2-sweep measurement is initiated. After the measurement is completed, the
system either stops (Measurement Trigger Mode = Single), or initiates another
2-sweep measurement (Measurement Trigger Mode = Continuous).
During the measurement, the button label changes to STOP MEASUREMENT. Once
the measurement is complete, the button label changes back to START AUTO
SCAN.
To stop a measurement
• Press STOP M EASUREMENT to stop a measurement in progress.
Selecting this softkey will stop the 2-sweep measurement cycle mid-sweep.
Once the measurement is stopped, the button label changes to START AUTOSCAN.
To select the external 9 µm fiber filter path
For Agilent 86144B/86146B only
The 9µm external optical path is used to increase dynamic range and resolution
bandwidth of the OSA.
1 Connect a 9 µm fiber between the Monochromator Output and the Photodetector
Input.
2 Connect a light source to the Optical Input.
3 Press Select Path > Path External > Switch Path Auto Align Now.
An auto align is performed on the 9 µm filter path mode. This aligns the output
of the monochromator with the photodetector input for improved amplitude
accuracy.
Once Auto Align is completed, the OSA will return to the previous
measurement state.
4 Press Start AutoScan to activate the external path and to update the measurement
data.
4-14
WDM Channel Analysis Application
Performing Measurements
Tip: If you want to proceed directly to using an external filter mode (Filter Mode
On), then the step above is not required.
To analyze a channel or wavelength
For Agilent 86144B/86146B only
The Agilent 86144B and 86146B filter mode allows a single channel or
wavelength from a dense wavelength division multiplex (DWDM) to be isolated
and routed to another measurement instrument. The filtering is accurate and
flexible. It has low polarization dependent loss (PDL), adjustable filter
bandwidth, and a wide tuning range.
1 Perform the procedure To select the external 9 µm fiber filter path
14.
The auto scan will identify and number the WDM channels. Using filter mode,
you can easily filter out any of the channels by number, to the front panel
Monochromator Output port.
2 Press Filter Mode On Off so that On is underlined.
3 Press Filter by WVL CH# to select the desired mode.
a Select WVL > Filter Wavelength to tune to a particular wavelength for further
analysis. For example, you can take the noise floor near a channel and route it to
a DCA plug-in module.
A triangle marker will appear at the selected wavelength.
b Select CH# > Filter Channel Number to select a particular channel to be filtered
out and routed to a DCA plug-in module to measure the power, or a bit error rate
tester to measure the Q factor.
A triangle marker will appear at the selected channel.
Note
If the input signal is changing, you may periodically want to update your measurement.
To do this, exit filter mode (Filter Mode Off) and then proceed in one of the two ways: 1.
Connect the OSA Monochromator Output to the Photodetector Input and Press Start
AutoScan. 2. Switch to the internal filter path (Filter Path Int) and press Start AutoScan.
4-15
WDM Channel Analysis Application
Performing Measurements
To display the results in a table
• Press the DISPLAY TABLE.... softkey. The results are displayed in a table similar to the one
shown below.
PAGE UP
display the previous page of results, if possible.
PAGE DOWN
display the next page of results, if possible.
DONE
exit the tabular display and return to the Auto Scan main menu.
4-16
WDM Channel Analysis Application
Performing Measurements
The WDM channel analysis application calculates the following statistics and
display the results at the bottom of the table:
•
•
•
•
•
•
•
•
•
•
•
Channel number for the channel with the maximum power
Maximum channel power (dBm)
Channel number for the channel with the minimum power
Minimum channel power (dBm)
Channel number for the channel with the maximum optical signal-to-noise ratio
Maximum optical signal-to-noise ratio (dB)
Channel number for the channel with the minimum optical signal-to-noise ratio
Minimum optical signal-to-noise ratio (dB)
Span tilt (dB/nm)
Span tilt (dB)
Peak-to-peak deviation, defined as:
maximum channel power – minimum channel power
Using a noise sweep resolution bandwidth of 0.06 nm, the maximum
wavelength span that can be measured is 75 nm. The maximum number of
WDM channels that can be measured is 187.
4-17
WDM Channel Analysis Application
Performing Measurements
To change the wavelength units in the table
1 Press the M EASUREMENT SETUP.... softkey. The following window opens.
Measurement Setup panel
2 Select the desired units for the table. You can select either nanometers or terahertz.
3 Press the CLOSE PANEL.... softkey when you are finished making your selections.
4-18
WDM Channel Analysis Application
Performing Measurements
To document measurement results
There are two ways to document results in the WDM Application. You can
either print them to a printer (specified under printer setup) or you can save
them to a floppy disk.
When the instrument is not sweeping, the DOCUMENT RESULTS... key of the WDM
Application Main Menu is enabled.
• Press the DOCUMENT RESULTS... softkey. The following window opens.
Document Results Menu
4-19
WDM Channel Analysis Application
Performing Measurements
To save the results to floppy
• Press the SAVE RESULTS TO FLOPPY softkey to save the current results to a file on the floppy drive.
The name of the file is defined as the last 8 characters of the ID. If no ID exists,
a message prompts the user to “Enter a Device ID as filename”. See “To enter a
device ID” on page 4-22 for additional information.
Save Dialog Panel and Menu
If the ID already exists, the warning “Overwrite File?” is displayed.
The current file is saved in .csv spreadsheet format.
4-20
WDM Channel Analysis Application
Performing Measurements
To print the results
1 Press the PRINT RESULTS softkey to print the results to the target printer.
The target printer is as set by factory default, otherwise it retains the previous
setting from the last time the application was started.
2 To change the target printer, press the PRINTER SETUP softkey.
3 The print operation is confirmed by a progress message displayed in the standard
progress panel used in the base instrument.
4-21
WDM Channel Analysis Application
Performing Measurements
To enter a device ID
• Press the ENTER ID... softkey to access the Device Identification panel
Device Identification panel
Entering characters and navigating this panel is explained in To use the
alphanumeric panel softkeys 27.
4-22
WDM Channel Analysis Application
Performing Measurements
To enter comments
• Press the ENTER COMMENTS... softkey to access the Enter Comments panel.
Enter Comments panel
Entering characters and navigating this panel is explained in To use the
alphanumeric panel softkeys 27.
4-23
WDM Channel Analysis Application
Performing Measurements
To set up the printer
1 Press the PRINTER SETUP softkey to access the Printer Setup panel.
The default setting is the internal printer and the default printout type is table
only.
2 Use the check boxes to select the target printer, either external or internal, and the
printout type. This setting is reset when the front-panel PRESET key is pressed,
otherwise the previous setting from the last time the application was started is
retained.
Printer Setup panel
Navigating and filling in the setup panel is explained in To fill in a setup panel
25.
PREVIOUS MENU...
Returns to the Auto Scan Menu.
To exit the application
• Press the EXIT APPLICATION softkey to exit the application.
4-24
WDM Channel Analysis Application
Performing Measurements
To fill in a setup panel
Any of the instrument settings can be changed by using either the front-panel
keys or the menu bar selections. Many of the menu selections and front-panel
keys display a softkey panel. Settings in softkey panels are changed using the
softkeys, data-entry keys, mouse, and trackball.
Setup panels, such as the Measurement Setup panel, allow you to adjust setup
conditions which are not frequently changed.
An example of a setup panel
4-25
Using the softkeys
The arrow softkeys
Allow you to navigate from field to field in the dialog box. The highlighted
parameter can be changed.
The Select softkey
Selects or deselects the highlighted parameter.
The Defaults softkey
Resets the parameters to their default condition.
Close Panel.... softkey
Saves the current setup and returns you to the previous menu.
The front-panel number keys, step keys, and knob
Allow you to enter a numeric value in the highlighted field.
WDM Channel Analysis Application
Performing Measurements
To use the alphanumeric panel softkeys
Alphanumeric panels, such as the Device Identification panel, allow you to
enter identification and comment labels for the devices you test.
An example of an alphanumeric panel
4-27
WDM Channel Analysis Application
Performing Measurements
Using the softkeys
The Select softkey
Selects the highlighted character.
The arrow softkeys
Allow you to navigate from character to character in the dialog box.
The Backspace softkey
Removes a previously selected character.
Continue.... softkey
Saves the current entry and returns you to the previous menu.
4-28
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
WDM Channel Analysis Remote Commands
The Agilent 86140B Series Optical Spectrum Analyzer Programming Guide for
the mainframe provides detailed information on remote programming of the
instrument. Only commands unique to the lightwave component analyzer are
included in this section.
The WDM channel analysis application remote command set is comprised of
two types of commands:
General Application support commands
These are part of the base firmware and support applications in general. These
commands allow the user to obtain a list of installed applications, load/unload
an application, and so on.
WDM channel analysis application specific commands
These remote commands are specific to the WDM channel analysis application
and allow you to control the WDM channel analysis application remotely. They
are grouped under the following subsystems:
• CALCulate Subsystem Commands
• CALibration Subsystem Commands
• FORMat Subsystem Commands
• INITiate Subsystem Commands
• INPut Subsystem Commands
• ROUTe Subsystem Commands
• SENSe Subsystem Commands
For more information, refer to the Remote Operation section in the Agilent
86140B Series Optical Spectrum Analyzer Programming Guide, or to the
following book:
4-29
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
SCPI Consortium. SCPI–Standard Commands for Programming Instruments, 1997
4-30
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
Command Conventions
Table 1
Convention
Description
<>
Angle brackets indicate text strings entered by the developer.
[]
Square brackets indicate that the keyword DEFAULT can be used instead
of a value or a variable for that parameter. Refer to the actual command
description for the behavior when the DEFAULT keyword is used for a
parameter.
|
Indicates a choice of one element from a list.
{}
Braces indicate a group of constants to select from. Each constant is
separated by the | character.
name
Indicates the variable for which you provide a descriptive name. Any letter
(Aa-Zz) followed by letters, digits (0-9) and underscore (_). Only the first 32
characters are significant.
spec_min
–infinity. The parameter spec_min cannot be a variable, only a constant or
DEFAULT.
spec_max
+infinity. The parameter spec_max cannot be a variable, only a constant or
DEFAULT.
from
Start wavelength or frequency of trace in nm (default) or THz.
to
Stop wavelength or frequency of trace in nm (default) or THz.
excursion
+excursion: means excursion dBs up (for example, from a pit).
-excursion: means excursion dBs down (for example, from a peak).
ref_pt
The reference point to be used for a measurement keyword.
4-31
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
CALCulate Subsystem Commands
The CALCulate subsystem performs post-acquisition data processing. The
CALCulate subsystem operates on data acquired by a SENSe function. For
more information, refer to page 4-1 of the 1997 SCPI Command Reference.
CALCulate:DATA:CPOWers?
This command allows the user to download the array of channel powers
measured. The data is returned in either an ASCII or binary form as determined
by the FORMat:DATA command. The number of data points in this array is
determined by the CALCulate:DATA:NCHannels? query.
CALCulate:DATA:CSNR?
This command allows the user to download the array of channel OSNR values
measured. The data is returned in either an ASCII or binary form as determined
by the FORMat:DATA command. The number of data points in this array is
determined by the CALCulate:DATA:NCHannels? query.
4-32
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
CALCulate:DATA:CSTats?
This command allows the user to download the following statistics using a
single query:
•
•
•
•
•
•
•
•
•
•
•
Channel number for the channel with the maximum power
Maximum channel power (dBm)
Channel number for the channel with the minimum power
Minimum channel power (dBm)
Channel number for the channel with the maximum optical signal-to-noise ratio
Maximum optical signal-to-noise ratio (dB)
Channel number for the channel with the minimum optical signal-to-noise ratio
Minimum optical signal-to-noise ratio (dB)
Span tilt (dB/nm)
Span tilt (dB)
Peak-to-peak deviation, defined as:
maximum channel power – minimum channel power
Using a noise sweep resolution bandwidth of 0.06 nm, the maximum
wavelength span that can be measured is 75 nm. The maximum number of
WDM channels that can be measured is 187.
The data is returned in either an ASCII or binary form as determined by the
FORMAT:DATA command.
CALCulate:DATA:CWAVelengths?
This command allows the user to download the array of channel wavelengths
measured. The data is returned in either an ASCII or binary form as determined
by the FORMat:DATA command. The number of data points in this array is
determined by the CALCulate:DATA:NCHannels? query. The units are either
nanometers or terahertz and can be changed using the
CALCulate:DATA:TABLe:WAVe command.
CALCulate:DATA:NCHannels?
This command allows the user to query the number of channels detected in the
last measurement. The data is returned as an ASCII integer.
4-33
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
CALCulate:DATA:TABLe:WAVe NM|THZ
CALCulate:DATA:TABLe:WAVe?
Sets the wavelength units used for the tabular display and for the
CALCulate:DATA:CWAVelengths remote query. The instrument x-axis display
always displays wavelength in nanometers and is not affected by this
command.
CALCulate:PEXCursion[:PEAK] <numeric_value>
CALCulate:PEXCursion[:PEAK]?
Sets the peak excursion value for the marker search routines. The peak
excursion value is used to determine whether or not a local maximum in the
trace is to be considered a peak. To qualify as a peak, both sides of the local
maximum must fall by at least the peak excursion value.
CALCulate:THReshold <numeric_value> [W|MW|UW|DBM]
CALCulate:THReshold?
Specifies the value for the peak search threshold. Peaks with amplitudes below
this value will not be included in the channel count.
Default units are DBM.
4-34
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
CALibration Subsystem Commands
This subsystem has the function of performing system calibration.
CALibration Alignment
Performs an automatic alignment of the instrument at the wavelength of the
largest signal found in full span. This aligns the monochromator output with
the photodetector for improved amplitude accuracy. Sending this command
with a marker on screen will generate a Settings conflict error.
Syntax
CAL:ALIG
Related Key
Auto Align
4-35
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
DISPlay Subsystem Commands
The DISPlay subsystem controls the selection and presentation of textual,
graphical, and TRACe information.
DISPlay[:WINDow]:DUT:COMMent<string>
Enters a new comment string for the device under test.
DISPlay[:WINDow]:DUT:COMMent?
Returns the comment string for the device under test.
DISPlay[:WINDow]:DUT[:ID]<string>
Enters a new identification string for the device under test.
DISPlay[:WINDow]:DUT[:ID]?
Returns the identification string for the device under test.
DISPlay[:WINDow[1]]:TRACe:Y[:SCALe]:RLEVel <numeric_value>[W|MW|UW|DBM]
DISPlay[:WINDow[1]]:TRACe:Y[:SCALe]:RLEVel?
Specifies the value of the reference level. Default units are DBM. Starting a
measurement from the front panel sets the reference level automatically based
on the maximum channel power. The reference level needs to be set manually
when using the instrument remotely.
4-36
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
FORMat Subsystem Commands
The FORMat subsystem sets a data format for transferring numeric and array
information.
FORMat[:DATA] REAL[32,64]|ASCII
FORMat[:DATA]?
Specifies the trace data format used during data transfer via HP-IB. This
command affects data transfers for the CALCulate[:DATA] subsystem. The
ASCII format is a comma-separated list of numbers. The REAL format is a
definite-length block of 64-bit floating-point binary numbers. The definitelength block is defined by IEEE 488.2: a "#" character, followed by one digit (in
ASCII) specifying the number of length bytes to follow, followed by the length
(in ASCII), followed by length bytes of binary data. The binary data is a
sequence of 8-byte (64-bit) floating point numbers.
4-37
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
INITiate Subsystem Commands
The INITiate subsystem is used to control the initiation of the TRIGger
subsystem.
INITiate:IMMediate
Initiates a new 2-sweep WDM measurement. This command is disabled when
in when INPut:FILTer[STATe] is ON.
4-38
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
INPut Subsystem Commands
The INPut subsystem is used to control the filter mode function. You must be in
filter mode to use the INPut:FILTer commands.
Note
The INPut subsystem commands are only available on the 86144B and 86146B.
INPut:FILTer:BANDwidth|BWIDth[:RESolution] <value>[wvl units]
INPut:FILTer:BANDwidth|BWIDth[:RESolution]?
Sets the resolution bandwidth of the filter. The query returns the filter’s
resolution bandwidth.
INPut:FILTer:BANDwidth|RESolution|AUTOmatic <ON|OFF>
INPut:FILTer:BANDwidth|RESolution|AUTOmatic?
Sets resolution bandwidth of the filter to automatic or manual mode. The query
returns the automatic or manual status.
INPut:CHANnel <channel number>
Sets the filter to the wavelength of the specified channel. The channel number
must be >0 and <=NUM_CHANNELS. There is no query associated with this
command. Instead you should use INPut:FILTer:WAVelength?.
INPut:FILTer[:STATe] <ON|OFF>
INPut:FILTer[:STATe]?
Turns the filter mode on/off. If the external path has not been selected, a
“Settings Conflict” error will be returned. IMITiate:IMMediate (sweeps) will be
disabled while in filter mode.
The query returns the status of the filter mode. The query returns a 1 if the filter
mode is on or returns a 0 if the filter mode is off.
4-39
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
INPute:FILTerWAVelength <value>
INPute:FILTerWAVelength?
Sets the filter to the specified wavelength. The query returns the wavelength
where the filter is currently set.
4-40
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
INSTrument Subsystem Commands
The INSTrument subsystem provides a mechanism to identify and select
logical instruments by either name or number. Arguments and responses are
case sensitive.
INSTrument:CATalog?
{OSA,PassiveComponent,WDM_AutoScan<null>}
Comma-separated list of strings representing the Modes and Applications
supported in the instrument.
INSTrument:CATalog:FULL?
{OSA,0,PassiveComponent,1,WDM_AutoScan,2}
Comma-separated list of string-numeric pairs representing the Modes and
Applications supported in the instrument.
INSTrument:SELect <identifier> identifier - string
INSTrument:NSELect <numeric_value>
INSTrument:NSELect?
Loads the application or instrument mode specified.
Example
INSTrument:SELect ”WDM_AutoScan”
INSTrument:NSELect 2
4-41
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
ROUTe Subsystem Commands
The ROUTe subsystem provides a mechanism to select the internal 50 µm or
external 9 µm path.
ROUTe:PATH <INTernal|EXTernal>
ROUTe:PATH?
Available for the 86144B and 86146B only.
Selects the internal 50 µm or external 9 µm path. This command is disabled
when in filter mode. The query will return the current path.
4-42
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
SENSe Subsystem Commands
The SENSe setup commands control the specific settings of the device.
SENSe:BANDwidth|BWIDth[:RESolution]:NOISe <numeric_value> [M|NM|UM|A]
SENSe:BANDwidth|BWIDth[:RESolution]:NOISe?
Specifies the resolution bandwidth value used for the ‘noise’ sweep in the 2sweep measurement mode. Default units are m.
SENSe:BANDwidth|BWIDth[:RESolution]:PEAK <numeric_value> [M|NM|UM|A]
SENSe:BANDwidth|BWIDth[:RESolution]:PEAK?
Specifies the resolution bandwidth value used for the ‘peaks’ sweep in the 2sweep measurement mode. Default units are m.
SENSe:CHANnel:SPACing <numeric_value> [HZ|KHZ|MHZ|GHZ]
SENSe:CHANnel:SPACing?
Specifies the value for channel spacing. Default units are GHz.
SENSe:NOISe [PIT|FIXED|HD]
SENSe:NOISe?
Specifies how the noise measurement locations are determined (pit, fixed
offset, or half-distance between channels).
4-43
WDM Channel Analysis Application
WDM Channel Analysis Remote Commands
SENSe:POWer[:DC]:RANGe:LOWer <numeric_value> [W|MW|UW|DBM]
SENSe:POWer[:DC]:RANGe:LOWer?
Specifies the sensitivity value used for the WDM channel analysis application
measurements. Default units are dBm.
NOTE
The maximum value for sensitivity is +300 dBm. The minimum value is the value that
causes the sweep time to become 1000 seconds, and is an attribute of each individual
optical spectrum analyzer. The minimum value will always be less than the values for
sensitivity shown in the Specifications section of the User’s Guide
SENSe:[WAVelength:]STARt <numeric_value> [M|NM|UM|A|HZ|KHZ|MHZ|GHZ]
SENSe:[WAVelength:]STARt?
Specifies the start wavelength for the WDM channel analysis application.
Default units are M.
SENSe:[WAVelength:]STOP <numeric_value> [M|NM|UM|A|HZ|KHZ|MHZ|GHZ]
SENSe:[WAVelength:]STOP?
Specifies the stop wavelength for the WDM channel analysis application.
Default units are M.
4-44
5
Contacting Agilent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Agilent Technologies Service Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Cleaning Connections for Accurate Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Customer Support
Customer Support
Contacting Agilent
Contacting Agilent
To learn more about your optical spectrum analyzer and other lightwave optical
communication test solutions, visit our Internet web site. Before returning an
instrument for service, call the Agilent Technologies Instrument Support Center
at (800) 403-0801, or visit the Agilent Lightwave web site at www.agilent.com/
find/assist. See “Agilent Technologies Service Offices” on page 5-3 for a list of
service centers.
5-2
Customer Support
Agilent Technologies Service Offices
Agilent Technologies Service Offices
Before returning an instrument for service, call the Agilent Technologies
Instrument Support Center at (800) 403-0801, or call one of the numbers listed
below.
Agilent Technologies Service Numbers
Austria
(43 1) 25125-7000
Belgium + Luxemburg
(02) 404.93.03
Brazil
(55 11) 7297-3700
Canada
888-447-7378
China
800-810-0508
France
01.69.82.66.69
Germany
01805 24 6337
Hong Kong
800-93-3229
India
91-80-343-5755
Ireland
01205 4500
Japan
0120-32-0119
Malaysia
1-800-880-399
Philippines
1-800-1651-0135
Singapore
1-800-275-0880
Spain
(34-91) 631 3300
Sweden
(08) 506 487 00
Switzerland
(+41 1) 735 9501
Taiwan
66 862 661 5900
United Kingdom
07004 123123
United States
(800) 403-0801
5-3
Customer Support
Cleaning Connections for Accurate Measurements
Cleaning Connections for Accurate Measurements
Today, advances in measurement capabilities make connectors and connection
techniques more important than ever. Damage to the connectors on calibration
and verification devices, test ports, cables, and other devices can degrade
measurement accuracy and damage instruments. Replacing a damaged
connector can cost thousands of dollars, not to mention lost time! This
expense can be avoided by observing the simple precautions presented in this
book. This book also contains a brief list of tips for caring for electrical
connectors.
5-4
Customer Support
Cleaning Connections for Accurate Measurements
Choosing the Right Connector
A critical but often overlooked factor in making a good lightwave measurement
is the selection of the fiber-optic connector. The differences in connector types
are mainly in the mechanical assembly that holds the ferrule in position against
another identical ferrule. Connectors also vary in the polish, curve, and
concentricity of the core within the cladding. Mating one style of cable to
another requires an adapter. Agilent Technologies offers adapters for most
instruments to allow testing with many different cables. Figure 1 on page 5-6
shows the basic components of a typical connectors.
The system tolerance for reflection and insertion loss must be known when
selecting a connector from the wide variety of currently available connectors.
Some items to consider when selecting a connector are:
• How much insertion loss can be allowed?
• Will the connector need to make multiple connections? Some connectors are better
than others, and some are very poor for making repeated connections.
• What is the reflection tolerance? Can the system take reflection degradation?
• Is an instrument-grade connector with a precision core alignment required?
• Is repeatability tolerance for reflection and loss important? Do your specifications take
repeatability uncertainty into account?
• Will a connector degrade the return loss too much, or will a fusion splice be required?
For example, many DFB lasers cannot operate with reflections from connectors. Often
as much as 90 dB isolation is needed.
5-5
Customer Support
Cleaning Connections for Accurate Measurements
Figure 1 Basic components of a connector.
Over the last few years, the FC/PC style connector has emerged as the most
popular connector for fiber-optic applications. While not the highest
performing connector, it represents a good compromise between performance,
reliability, and cost. If properly maintained and cleaned, this connector can
withstand many repeated connections.
However, many instrument specifications require tighter tolerances than most
connectors, including the FC/PC style, can deliver. These instruments cannot
tolerate connectors with the large non-concentricities of the fiber common
with ceramic style ferrules. When tighter alignment is required, Agilent
Technologies instruments typically use a connector such as the Diamond HMS10, which has concentric tolerances within a few tenths of a micron. Agilent
Technologies then uses a special universal adapter, which allows other cable
types to mate with this precision connector. See Figure 2.
Figure 2 Universal adapters to Diamond HMS-10.
5-6
Customer Support
Cleaning Connections for Accurate Measurements
The HMS-10 encases the fiber within a soft nickel silver (Cu/Ni/Zn) center
which is surrounded by a tough tungsten carbide casing, as shown in Figure 3.
Figure 3 Cross-section of the Diamond HMS-10 connector.
The nickel silver allows an active centering process that permits the glass fiber
to be moved to the desired position. This process first stakes the soft nickel
silver to fix the fiber in a near-center location, then uses a post-active staking
to shift the fiber into the desired position within 0.2 µm. This process, plus the
keyed axis, allows very precise core-to-core alignments. This connector is
found on most Agilent Technologies lightwave instruments.
The soft core, while allowing precise centering, is also the chief liability of the
connector. The soft material is easily damaged. Care must be taken to minimize
excessive scratching and wear. While minor wear is not a problem if the glass
face is not affected, scratches or grit can cause the glass fiber to move out of
alignment. Also, if unkeyed connectors are used, the nickel silver can be
pushed onto the glass surface. Scratches, fiber movement, or glass
contamination will cause loss of signal and increased reflections, resulting in
poor return loss.
5-7
Customer Support
Cleaning Connections for Accurate Measurements
Inspecting Connectors
Because fiber-optic connectors are susceptible to damage that is not
immediately obvious to the naked eye, poor measurements result without the
user being aware. Microscopic examination and return loss measurements are
the best way to ensure good measurements. Good cleaning practices can help
ensure that optimum connector performance is maintained. With glass-toglass interfaces, any degradation of a ferrule or the end of the fiber, any stray
particles, or finger oil can have a significant effect on connector performance.
Where many repeat connections are required, use of a connector saver or
patch cable is recommended.
Figure 4 shows the end of a clean fiber-optic cable. The dark circle in the center
of the micrograph is the fiber’s 125 µm core and cladding which carries the
light. The surrounding area is the soft nickel-silver ferrule. Figure 5 shows a
dirty fiber end from neglect or perhaps improper cleaning. Material is smeared
and ground into the end of the fiber causing light scattering and poor reflection.
Not only is the precision polish lost, but this action can grind off the glass face
and destroy the connector.
Figure 6 shows physical damage to the glass fiber end caused by either
repeated connections made without removing loose particles or using
improper cleaning tools. When severe, the damage of one connector end can
be transferred to another good connector end face that comes in contact with
the damaged one. Periodic checks of fiber ends, and replacing connecting
cables after many connections is a wise practice.
The cure for these problems is disciplined connector care as described in the
following list and in Cleaning Connectors 12.
Use the following guidelines to achieve the best possible performance when
making measurements on a fiber-optic system:
• Never use metal or sharp objects to clean a connector and never scrape the connector.
• Avoid matching gel and oils.
5-8
Customer Support
Cleaning Connections for Accurate Measurements
Figure 4 Clean, problem-free fiber end and ferrule.
Figure 5 Dirty fiber end and ferrule from poor cleaning.
Figure 6 Damage from improper cleaning.
While these often work well on first insertion, they are great dirt magnets. The
oil or gel grabs and holds grit that is then ground into the end of the fiber. Also,
some early gels were designed for use with the FC, non-contacting connectors,
5-9
Customer Support
Cleaning Connections for Accurate Measurements
using small glass spheres. When used with contacting connectors, these glass
balls can scratch and pit the fiber. If an index matching gel or oil must be used,
apply it to a freshly cleaned connector, make the measurement, and then
immediately clean it off. Never use a gel for longer-term connections and never
use it to improve a damaged connector. The gel can mask the extent of damage
and continued use of a damaged fiber can transfer damage to the instrument.
• When inserting a fiber-optic cable into a connector, gently insert it in as straight a line
as possible. Tipping and inserting at an angle can scrape material off the inside of the
connector or even break the inside sleeve of connectors made with ceramic material.
• When inserting a fiber-optic connector into a connector, make sure that the fiber end
does not touch the outside of the mating connector or adapter.
• Avoid over tightening connections.
Unlike common electrical connections, tighter is not better. The purpose of the
connector is to bring two fiber ends together. Once they touch, tightening only
causes a greater force to be applied to the delicate fibers. With connectors that
have a convex fiber end, the end can be pushed off-axis resulting in
misalignment and excessive return loss. Many measurements are actually
improved by backing off the connector pressure. Also, if a piece of grit does
happen to get by the cleaning procedure, the tighter connection is more likely
to damage the glass. Tighten the connectors just until the two fibers touch.
• Keep connectors covered when not in use.
• Use fusion splices on the more permanent critical nodes. Choose the best connector
possible. Replace connecting cables regularly. Frequently measure the return loss of the
connector to check for degradation, and clean every connector, every time.
All connectors should be treated like the high-quality lens of a good camera.
The weak link in instrument and system reliability is often the inappropriate
use and care of the connector. Because current connectors are so easy to use,
there tends to be reduced vigilance in connector care and cleaning. It takes
only one missed cleaning for a piece of grit to permanently damage the glass
and ruin the connector.
5-10
Customer Support
Cleaning Connections for Accurate Measurements
Measuring insertion loss and return loss
Consistent measurements with your lightwave equipment are a good
indication that you have good connections. Since return loss and insertion loss
are key factors in determining optical connector performance they can be used
to determine connector degradation. A smooth, polished fiber end should
produce a good return-loss measurement. The quality of the polish establishes
the difference between the “PC” (physical contact) and the “Super PC”
connectors. Most connectors today are physical contact which make glass-toglass connections, therefore it is critical that the area around the glass core be
clean and free of scratches. Although the major area of a connector, excluding
the glass, may show scratches and wear, if the glass has maintained its
polished smoothness, the connector can still provide a good low level return
loss connection.
If you test your cables and accessories for insertion loss and return loss upon
receipt, and retain the measured data for comparison, you will be able to tell in
the future if any degradation has occurred. Typical values are less than 0.5 dB
of loss, and sometimes as little as 0.1 dB of loss with high performance
connectors. Return loss is a measure of reflection: the less reflection the better
(the larger the return loss, the smaller the reflection). The best physically
contacting connectors have return losses better than 50 dB, although 30 to
40 dB is more common.
Visual inspection of fiber ends
Visual inspection of fiber ends can be helpful. Contamination or imperfections
on the cable end face can be detected as well as cracks or chips in the fiber
itself. Use a microscope (100X to 200X magnification) to inspect the entire end
face for contamination, raised metal, or dents in the metal as well as any other
imperfections. Inspect the fiber for cracks and chips. Visible imperfections not
touching the fiber core may not affect performance (unless the imperfections
keep the fibers from contacting).
WARN ING
Always remove both ends of fiber-optic cables from any instrument,
system, or device before visually inspecting the fiber ends. Disable all
optical sources before disconnecting fiber-optic cables. Failure to do
so may result in permanent injury to your eyes.
5-11
Customer Support
Cleaning Connections for Accurate Measurements
Cleaning Connectors
The procedures in this section provide the proper steps for cleaning fiber-optic
cables and Agilent Technologies universal adapters. The initial cleaning, using
the alcohol as a solvent, gently removes any grit and oil. If a caked-on layer of
material is still present, (this can happen if the beryllium-copper sides of the
ferrule retainer get scraped and deposited on the end of the fiber during
insertion of the cable), a second cleaning should be performed. It is not
uncommon for a cable or connector to require more than one cleaning.
CAUTION
Agilent Technologies strongly recommends that index matching compounds not
be applied to their instruments and accessories. Some compounds, such as
gels, may be difficult to remove and can contain damaging particulates. If you
think the use of such compounds is necessary, refer to the compound
manufacturer for information on application and cleaning procedures.
Table 1 Cleaning Accessories
Item
Agilent Part Number
Cotton swabs
8520-0023
Small foam swabs
9300-1223
Table 2 Dust Caps Provided with Lightwave Instruments
Item
Agilent Part Number
Laser shutter cap
08145-64521
FC/PC dust cap
08154-44102
Biconic dust cap
08154-44105
5-12
Customer Support
Cleaning Connections for Accurate Measurements
To clean a non-lensed connector
CAUTION
Do not use any type of foam swab to clean optical fiber ends. Foam swabs can
leave filmy deposits on fiber ends that can degrade performance.
5-13
Customer Support
Cleaning Connections for Accurate Measurements
1 Apply pure isopropyl alcohol to a clean lint-free cotton swab or lens paper.
Cotton swabs can be used as long as no cotton fibers remain on the fiber end after
cleaning.
2 Clean the ferrules and other parts of the connector while avoiding the end of the fiber.
3 Apply isopropyl alcohol to a new clean lint-free cotton swab or lens paper.
4 Clean the fiber end with the swab or lens paper.
Do not scrub during this initial cleaning because grit can be caught in the swab
and become a gouging element.
5 Immediately dry the fiber end with a clean, dry, lint-free cotton swab or lens paper.
6 Blow across the connector end face from a distance of 6 to 8 inches using filtered,
dry, compressed air. Aim the compressed air at a shallow angle to the fiber end face.
Nitrogen gas or compressed dust remover can also be used.
CAUTION
Do not shake, tip, or invert compressed air canisters, because this releases
particles in the can into the air. Refer to instructions provided on the
compressed air canister.
7 As soon as the connector is dry, connect or cover it for later use.
If the performance, after the initial cleaning seems poor, try cleaning the
connector again. Often a second cleaning will restore proper performance. The
second cleaning should be more arduous with a scrubbing action.
To clean an adapter
The fiber-optic input and output connectors on many Agilent Technologies
instruments employ a universal adapter such as those shown in the following
picture. These adapters allow you to connect the instrument to different types
of fiber-optic cables.
Figure 7 Universal adapters.
5-14
Customer Support
Cleaning Connections for Accurate Measurements
1 Apply isopropyl alcohol to a clean foam swab.
Cotton swabs can be used as long as no cotton fibers remain after cleaning. The foam
swabs listed in this section’s introduction are small enough to fit into adapters.
Although foam swabs can leave filmy deposits, these deposits are very thin, and the risk
of other contamination buildup on the inside of adapters greatly outweighs the risk of
contamination by foam swabs.
2 Clean the adapter with the foam swab.
3 Dry the inside of the adapter with a clean, dry, foam swab.
4 Blow through the adapter using filtered, dry, compressed air.
Nitrogen gas or compressed dust remover can also be used. Do not shake, tip, or invert
compressed air canisters, because this releases particles in the can into the air. Refer
to instructions provided on the compressed air canister.
5-15
Customer Support
Cleaning Connections for Accurate Measurements
5-16
www.agilent.com
Agilent Technologies GmbH 2006
Printed in Germany February 2006
Second edition, February 2006
Agilent Technologies
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