Optimized few-mode EDFA of applicability for variable mode groups with an extended doping region and a PSO algorithm

Abstract

We employ particle swarm optimization to present a cladding-pumped few-mode erbium-doped fiber amplifier (FM-EDFA) with an extended erbium-doped distribution over the core. By enlarging the radius of the doping region to improve the gain of high-order modes, the differential modal gain (DMG) can be minimized. The proposed FM-EDFA can provide average gain of 21.7 dB and DMG of less than 0.61 dB across the C-band (1530–1565 nm) for seven-mode groups. In addition, the value of the optimal doping radius has been investigated for different numbers of mode groups, which will gradually increase with the number of mode groups. Finally, simulation results indicate acceptable applicability for four- to six-mode groups even using the proposed design.