Abstract:In this paper, we have mainly studied the amplification effect of thulium-doped fiber amplifier(TDFA) at 2μm, and compared the different amplification effects of the one-stage TDFA, two-stage TDFA and three-stage TDFA at proper conditions, we can understand the influences of each factor on the amplification efficiency of 2μm TDFA. The simulation results show that, within the effective threshold, with the increase of the pump power, the amplification effect of the optical amplifier improves, but the signal-to-noise ratio(SNR) of the output signal decreases, in order to balance the gain benefit and noise coefficient of TDFA, we can use a multi-stage amplification structure, finally, a 2μm TDFA with good gain and noise can be obtained. Three-stage backward-pumped series 2.06μm TDFA, which slope efficiency can be achieved 11% at certain condition. At 5.2W pump power, the output signal gain exceeds 20dB, and the output SNR is higher than 32dB. In addition, the effects of wavelength and fiber length on the signal amplification of 2.06?m TDFA are also simulated, and good results are obtained. The advantages and disadvantages of 2.06μm TDFA with different structures under different conditions are also analyzed. The simulation results of these TDFA are compared comprehensively with each other, and the amplifying effects of different TDFA are compared, the importance of optimum length of thulium-doped fiber for 2μm TDFA is analyzed. The simulation results are of great significance for the experiment and design of TDFA at 2μm.