Tutorial.pdf

Lesson 10: Optimization of the gain flatness of
broadband Raman amplifiers
The flatness of the gain of inline fiber amplifiers is a matter of primary importance for WDM
systems. This lesson will demonstrate how to optimize further the gain uniformity of the Raman
amplifier described in “Lesson 9: Design of a broadband Raman amplifier using subsystems”.
There are numerous parameters that influence considerably the performance of Raman
amplifiers, but the most easily controlled one is probably the fiber length.
Optimizing the length of the fiber
First we set the mode of the parameter “Fiber Length” to “Sweep”. Next we adjust the number of
iterations to 13 by using the sequence of steps described in Changing the number of sweep
iterations.
Next we define range of values for the fiber length from 10 to 40 km, as shown in Changing the
values of sweep iterations.
Figure 95 - “Sweeping” the length of the broadband gain-flattened Raman amplifier
Next we have to add the “Results” “Maximal Forward Gain [dB]” and “Forward Gain Flatness [dB]”
to the results display table as shown in the following figure:
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