Atec Agilent-8156A - Manual (Page 2)

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Modular Design for Lightwave Solution Platform
Agilent’s 8157xA variable optical attenuators are a family
of plug-in modules for Agilent’s Lightwave Solution
Platform 8163A/B, 8164A/B and 8166A/B. The attenuator
modules 81570A, 81571A and 81578A occupy one slot,
while modules 81576A and 81577A occupy two slots. With
17 slots, the Agilent 8166A/B Lightwave Multichannel
System can host up to 17 single slot modules or up to 8
dual slot modules.
Variable Optical Attenuators
The Agilent 81570A, 81571A and 81578A are small, cost-
effective attenuator modules with high resolution. They
feature excellent wavelength flatness and can handle high
input power levels. Combined with their low insertion loss,
they are ideal for optical amplifier test, such as
characterization of EDFAs and of Raman amplifiers, as
well as for other multi-wavelength applications, such as
DWDM transmission system test. Various calibration
features allow the user to set a reference power. Both the
attenuation and the power level, relative to the reference
power, can then be set and displayed in the user interface.
An integrated shutter, which can be used for protection
purposes, or to simulate channel drops, is included.
The multimode 81578A brings this performance to
multimode test and can be ordered for 50 µm or 62.5 µm
fiber.
Attenuators with Power Control
Agilent’s 81576A and 81577A attenuators feature power
control functionality that allows you to set the output
power level of the attenuator. The attenuator module uses
the feedback signal from a photodiode after a monitor tap,
both integrated in the module, to set the desired power
level at the output of the module. When the power control
mode is enabled, the module automatically corrects power
changes at the input to maintain the output level set by the
user. After an initial calibration for the uncertainties at
connector interfaces, absolute power levels can be set
with high accuracy. The absolute accuracy of these power
levels depends on the accuracy of the reference power
meter used for calibration.
These modules also feature high power handling capability
and excellent wavelength flatness for DWDM applications.
To set a total power level of a multi-wavelength signal, it is
necessary to determine the convolution of the signal’s
spectrum with the sensitivity of the photodiode over
wavelength. An enhanced calibration feature supports this
process and enables setting the integral power of a
DWDM signal with a known spectrum.