Chirped fiber Bragg grating enabled mode-dependent gain equalization of 2-mode EDFA

We report a few-mode chirped fiber Bragg grating (FM-CFBG) enabled mode-dependent gain (MDG) equalizer for the all-fiber FM-EDFA. Relying on the mode-dependent reflectivity of the FM-CFBG, the MDG arising in an all -fiber 2-mode EDFA can be effectively mitigated. With the LP01 pump light injection, the average gain is up to 17 dB while the MDG can be equalized to be less than 1.26 dB within the reflection bandwidth of FM-CFBG. The MDG equalizer based on a FM-CFBG is equipped with several merits of compact size, low insertion loss, and wavelength scalability, which is meaningful for long-haul MDM transmission.