Theoretical analysis of characteristics for 2 μm Tm3+:Ho3+ co-doped silica fiber laser pumped by a 1550 nm fiber laser

We established a theoretical model of 2 μm Tm3+:Ho3+ co-doped silica fiber laser pumped by a 1550 nm fiber laser based on the rate-equation theory and performed the numerical simulation using Runge–Kutta algorithm and Newton–Raphson algorithm. The intracavity power distributions of both pump and laser of the Tm3+:Ho3+ co-doped silica fiber laser based on the Tm3+:Ho3+ co-doped silica fiber supplied by the National Optics Institute in Canada (NOIC) were obtained. The effects of the output reflectivity R4(λs) at the output laser wavelength λs and the concentrations of Tm3+ and Ho3+ in the fiber on laser output performance were analyzed. In order to achieve a high laser output power, the optimal R4(λs) of 0.13 was verified and the optimal Tm:Ho ratio of 1:2.4 was proposed. Finally, better output performance for the fiber laser based on the optimized Tm3+:Ho3+ co-doped silica fiber was obtained than the laser using the fiber supplied by the NOIC. This theoretical model and numerical simulation results will guide the fabrication of 2 μm Tm3+:Ho3+ co-doped all-fiber lasers pumped by 1600-nm-band (1500–1750 nm) Er3+:Yb3+ co-doped silica fiber lasers.

► Proposing the idea of 2-μm-band all-fiber Tm3+:Ho3+ co-doped silica fiber laser.
► Establishing theoretical model of Tm3+:Ho3+ fiber laser pumped by a 1550 nm laser.
► Proposing the optimal Tm:Ho ratio of 1:2.4.
► Obtaining better performance for 2 μm fiber laser based on the optimized ratio.