Dispersion management and gain flattened for a bridge-type hybrid amplifiers in a pumping recycling mechanism

We propose a hybrid C+L band fiber amplifier loop-back scheme which is composed of a C-band erbium-doped fiber amplifier (EDFA) and an L-band Raman fiber amplifier (RFA) using double-pass dispersion compensators in a loop-back scheme (also named as bridge scheme). Dispersion slope mismatch are precisely compensated for all 14 C+L band channels by writing fiber Bragg gratings (FBGs) at appropriate locations. Gain variation among multiple channels can be reduced from 6.5 dB to ±0.2 dB. The overall pump efficiency is 25% improved for C band signals by recycling the residual pump power. With several merits as mentioned, the hybrid EDFA/RFA may find potential applications in WDM long-haul systems and optical networks.