Multi-pump optimization for Raman+EDFA hybrid amplifiers under pump residual recycling

A new technique to optimize the gain profile of broadband hybrid amplifiers is here proposed. It is based on the equalization of Erbium's gain spectrum by adjusting the flexible gain profile of a multi-pump Raman amplification stage. However, for increased power pump efficiency, the residual Raman pump is recycled by the Erbium-doped section. This hybrid amplifier is assessed in terms of single-channel global gain, ripple, and noise figure. Ripple values below 1 dB have been found in a bandwidth of approximately 30 nm under two and three pump configurations.