Amplification and Transmission System With Matching Multi-Layer Ion-Doped FM-EDFA

System stability and robustness are highly desired in a mode division multiplexing (MDM) transmission system. The matching of the active fiber and transmission FMF effectively reduces the transmission impairments and is conducive to transmission stability. In this paper, we proposed and fabricated a well-matched triple-layered-core few-mode erbium-doped fiber (FM-EDF) for low differential modal gain (DMG) with multilayer ions doping adjustment. Based on the fabricated FM-EDF, the amplifier is constructed experimentally. By a simple LP₀₁ pump mode, the modal gains are higher than 24 dB, and meanwhile, the DMG of 1.6 dB is obtained. The compatibility between the FM-EDF and the passive transmission FMF is verified in an MDM transmission system with a matching degree higher than 83%. Results show that after long-haul FMF transmission and single-stage amplification, the difference in the output signal power is lower than 1.8 dB at the receiver. The fabricated FM-EDF is beneficial for practical MDM systems with high mode stability, excellent fiber linkage integration, and signal channel equalization, which shows much potential for long-haul MDM transmission and multistage amplification.