High-power broadband amplification around 2.3 μm in thulium-doped fluorotellurite glass fibers

We demonstrate high-power broadband amplification around 2.3 μm in thulium-doped fluorotellurite fibers (TDFTFs) pumped by a 1410 nm fiber laser. The TDFTFs, based on TeO 2 -BaF 2 -Y 2 O 3 (TBY) glass, were fabricated using a rod-in-tube method. The as-fabricated TDFTFs have a core diameter of ∼7 µm and a Tm 3+ doping concentration of about 4000 ppm. Using a 2.0-m-long TDFTF as the gain medium, a maximum output power of ∼3.06 W is experimentally achieved under an input signal power of 176.5 mW at 2300 nm and an absorbed pump power of 6.42 W, corresponding to a power conversion efficiency (PCE) of ∼44.9%. Moreover, broadband amplification was realized over the spectral range of 2265-2365 nm. With a fixed input signal power of 1 mW, the measured output power exceeded 1.89 W across the entire working bandwidth. Furthermore, numerical simulations of high-power amplification in TDFTFs were conducted to explore their power-scaling capability at 2.3 μm. The calculated results show excellent consistency with experimental measurements, demonstrating that the proposed TDFTFs have the potential for developing ten-watt-level fiber amplifiers operating around 2.3 μm.