Abstract
A fiber loop mirror (FLM) equalizer module is presented to solve the gain differential problem in cascaded erbium-doped fiber amplifiers (EDFAs) used in wavelength division multiplexing (WDM). Observations show that the maximum power differential is reduced from 30 dB to 2 dB for three WDM channels covering a 9-nm wavelength range. The filter peak wavelength can be tuned by greater than 7 nm by varying the polarization inside the fiber loop mirror. This polarization variation also modifies the filter shape and filter bandwidth allowing greater flexibility and robustness in dynamic system performance.