Multimode EDFA With Scalable Mode Selective Gain Control at 1480-nm Pump Wavelength

Erbium-doped fiber amplifiers are a promising solution for the signal amplification in long-haul mode-division multiplexed transmission systems. In order to minimize signal degradations by these amplifiers, low mode dependent gain and noise figures are desirable. We propose a scalable mode dependent gain equalization scheme for the 1480-nm pump wavelength. Contrary to the 980-nm pump wavelength, each signal mode has a maximum overlap with only one pump mode. Due to this, a scalable mode selective gain control is achievable by adjusting the pump modes. In this letter, we demonstrate the scalability of our approach with the number of signal modes by numerical simulation. Furthermore, we propose a two-stage amplifier setup in which the mode dependent gain of both stages is compensated in the second stage, pumped at a wavelength of 1480 nm.