Six-Mode Extended L-Band Edfa With A Low Differential Modal Gain

We report a numerical investigation on a trench-assisted few-mode erbium-doped fiber amplifier supporting 6 spatial modes with a very low differential modal gain. The numerical investigation is based on the experimentally measured parameters of extended L-band Er3+ doped fiber. The results show that the differential modal gain of 6 spatial modes covering the spectral range from 1570 to 1616 nm was reduced to as low as 0.28 dB by a mode hybrid core pumped architecture at a 1550 nm pump wavelength. Compared with cladding pumping, our method achieved a gain efficiency increased by 23.1% and a smaller differential modal gain when both average gains reached 20 dB. It is suggested that our investigation shows great potential for decreasing the differential modal gain effectively. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement