Optimization of super-Gaussian thulium-doped fiber amplifier for S-band multimode division multiplexing

Abstract

We have assigned the first four linear polarized (LP) modes of signals at the wavelength of 1470 nm as four channels of multimode division multiplexing (MDM) structure and for each channel we have used a few-mode thulium doped fiber amplifier (FM-TDFA) consisting a pump at the wavelength of 1050 nm and a few-mode thulium doped fiber (FM-TDF). The operation of each FM-TDFA has been investigated by changing the three parameters of super-Gaussian transverse distribution of FM-TDF in the presence of different kinds of LP modes of pumping with several values of input pump power. We have searched the whole space of variables through computation of the rate and power equations and calculated the overlap factors, gain and noise figure (NF) for each point of the space to find the global optimum condition. Also, we have found the best FM-TDFAs configurations by the average gain of 39.2 dB and average NF of 3.24 dB.