Rigorous and optimized few-mode erbium-doped fiber amplifier design by using topology optimization and genetic algorithms

We develop a rigorous procedure for the optimum design of few-mode erbium (Er)-doped fiber amplifiers, which is tackled as a multiobjective optimization problem, in an approach based on the combination of the topology optimization and genetic algorithm techniques. We demonstrated that the usual ring-like doping distributions are necessarily the best choices only if the pump intensity shows no azimuthal dependence. Additionally, in general, the optimum doping distribution will be a function of the signal and pump azimuthal mode numbers. For the particular case of the LP11 pump, we also provide a triple-ring Er-doping profile that maximizes modal equalization for seven-group modes over the whole C-band, the highest modal count proposed in the literature so far. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)