Equalization of nonuniform EDFA gain using a fiber-loop mirror

We have experimentally demonstrated cascaded EDFA gain equalization using a fiber-loop mirror (FLM) acting as a linear wavelength filter. By changing the intra-loop polarization, the FLM passband center wavelength can be tuned. Additionally, there is some ability to change the bandwidth and filter slope of the FLM. The FLM is used to equalize the nonuniform gain of a cascade of EDFAs. After 1500 km, the power differential is reduced from 30 to 2 dB for three WDM channels covering a 9-nm wavelength range.