Optimized Two-Stage Few-Mode Erbium Doped Fiber Amplifier

Few-mode erbium-doped fiber amplifiers (FM-EDFAs) are key elements in the development of Space Division Multiplexing systems based on few-mode fibers. In this work, through numerical simulation, we designed a two-stage FM-EDFA, minimizing both the differential spectral gain (DSG) and the differential modal gain (DMG) by means of a gain-flattening filter and pumping optimized through a genetic algorithm. By propagating 9 WDM signals in each of 6 LP modes and using 3 pumping modes, we kept the DMG and DSG below 3 dB and 0.6 dB, respectively; with a mean gain 17 dB and NF below 5 dB, along the all C-band.