i also want to share Advantages & Disadvantages of FRA
Advantages:
Variable wavelength amplification possible , Compatible with installed SM fiber , Can be used to extend EDFAs , Can result in a lower average power over a span, good for lower crosstalk , Very broadband operation may be possible.
Disadvantages:
High pump power requirements, high pump power lasers have only recently arrived , Sophisticated gain control needed , Noise is also an issue
So, at the end i would like to say that we have different parameters to seek for usage of optical amplifiers Pumping power, desired band of operation, gain, attenuation and its applications.
Hope you find it helpful.
Thanks