High-gain single-frequency Tm3+-doped ZBLAN fiber amplifier at 2.33 mu m

We report here, to the best of our knowledge, the first highgain, single-frequency Tm3+-doped fiber amplifier operating at the 2.3-mu m band with conventional ground-state pumping transition (H-3(6)-> H-3(4)) at 793 nm. The gain fiber is an 8.5-m-long ZBLAN fiber with a Tm3+ doping concentration of 3 mol.%, and the seed is a single-frequency distributed feedback diode laser operated at 2331.9 nm. A gain up to 24.1 dB is generated for similar to 14 W of launched pump power with the maximum output power of 246 mW. The competitive F-3(4) -> H-3(6) laser transition at similar to 2 mu m is also investigated, and the prospects for further power scaling are discussed. (c) 2023 Optica Publishing Group