Optimum design of few-mode EDFAs by using topology optimization

The optimum design of FM-EDFAs is rigorously tackled as a multi-objective optimization problem, in a novel approach based on the topology optimization technique. It is demonstrated that the usual ring-like doping distributions are optimum choices only if the pump intensity shows no azimuthal dependence. For this symmetrical case, displaying no azimuthal variation, we provide an optimum double-ring Er doping profile which maximizes modal equalization for six-group modes.