Modeling and Characterization of a Multimode EDFA Supporting Four Transverse Mode Groups for Modal Division Multiplexed Transmissions

Numerical and experimental study of a multi-mode (MM) Erbium Doped Fiber Amplifier (EDFA) suitable for mode division multiplexing (MDM) is reported. Based on numerical simulations, a Few Mode Erbium Doped Fiber (FM-EDF) has been designed to support 4 mode groups and to equally amplify LP11 & LP21 mode groups with gains close to 20 dB and with a differential gain between these modes of less than 1dB. Experimental results confirmed the simulations with a good concordance. This modal gain equalization is obtained by tailoring the erbium spatial distribution in the fiber core with a ring-shaped profile.