Optimization of the Erbium Doping Profile in Erbium-Doped Fiber Amplifiers for Mode-Division Multiplexing

Abstract:
Mode-division multiplexing is a promising solution to increase the capacity per fiber well beyond the capacity limits of single mode fiber systems. In order to enable signal amplification for these systems, multimode erbium-doped fiber amplifiers with low mode dependent gain and noise figures for all signal modes have to be developed. In this work we numerically investigate gain equalization for these amplifiers by tailoring the erbium doping profile. We show that in theory decent gain equalization is possible for step-index fibers as well as for graded-index fibers. Furthermore, we show that omitting some higher order modes reduces the complexity of the resulting erbium doping profile.