Improved designs for short wavelength amplification based on a thulium-doped Ta2O5 waveguide

Abstract

Abstract This study aims to design a thulium-doped Ta2O5 amplifier for short wavelength amplification at 1.7 µm waveband. The waveguide width of the proposed design is theoretically optimized to ensure the condition of single mode guidance and the appropriate width must be less than 3.2 µm. Finite element method based edge element is applied to compute the optical field distribution of the fundamental mode across the waveguide length and to find the values of the overlapping factor and the effective mode field area of the proposed waveguide. The numerical results display that 0.83 and 6.8 µm2 are the computed values of the overlapping factor and the effective mode field area, respectively at 1.72 µm wavelength. The amplification performance of a Tm:Ta2O5 amplifier is presented based on the rate equations and the power distribution equations. The effects of the waveguide length and the pump power are investigated on the signal amplification at 1.72 µm wavelength. The simulation results reveal that about 25 dB small signal gain and 8.7 dB noise figure could be achieved at 1.72 µm wavelength when pumped with only 100 mW pump power at 1630 nm wavelength. As a result, it is possible to achieve an efficient laser and amplifier source at the 1.7 µm waveband based on a Tm:Ta2O5 waveguide.