Setting Attenuation and/or Power Levels How to Use a Variable Optical Attenuator module
190 Agilent 8163A/B, 8164A/B, and 8166A/B User’s Guide, Fourth Edition
How to Set a Power Level
Single-wavelength signals Set the λ parameters to the wavelength of the source.
You can edit P
SET
to set the power output of the Attenuator directly.
Multi-wavelength DWDM signals If you wish to set the output power of a multi-wavelength DWDM
signal, use an 8157xA Attenuator module, since these modules include
a filter with minimum wavelength dependency.
The 81576A and 81577A modules incorporate a powermeter whose
responsivity varies over wavelength. The module-specific response
data is accessible via a computer interface, so an effective wavelength
λ
effective
for your input signal’s optical spectrum can be determined
most readily, but not exclusively, by using the hp816x VXI PnP
Spectral Calibration function (hp816x_spectralCalibration).
Refer to:
• Measuring the Dependence of Optical Amplifiers on Input Power
Using an Attenuator. Application Note.
Agilent Technologies publication number 5988-5260EN.
• Agilent 8163A/B Lightwave Multimeter, Agilent 8164A/B Lightwave
Measurement System, and Agilent 8166A/B Lightwave Multichannel
System, Programming Guide, part number 08164-90B63 (or a later
edition).
NOTE For accurate power measurements, the simple weighted wavelength of
a multi-wavelength DWDM signal is insufficient.
Calibrating Test Setups that use an
81560A/61A/70A/71A/73A Attenuator module
Requirement for Calibration P
SET
is a relative measurement that is meaningful only after your test
setup has been calibrated against a reference powermeter.
Preconditions • To make the calibration as quick and simple as possible, host your
reference powermeter in the same mainframe as the Attenuator
module, as described in “Hosting a Reference Powermeter” on
page 183.
• Before taking a power measurement, make sure the source is
warmed up so that its power output is stable.
• It is good practice to zero the reference powermeter before
calibrating your test setup. Refer to “How to Remove Electrical
Offsets” on page 85.
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