If that’s what you are interested in, you may a look at the following links about the amplification laser schemes that I’ve mentioned above: http://optoelectronics.ece.ucsb.edu/sites/default/files/publications/wang05jlt.pdf
http://gratings.fo.gpi.ru/pdf/QE_2001_31__801_Kurkov_EDFA_Raman_pumped_eng.pdf