Highly efficient continuous-wave and ReSe2 Q-switched ∼3 μm dual-wavelength Er:YAP crystal lasers

We report on continuous-wave (CW) and rhenium diselenide (ReSe2) Q-switched dual-wavelength mid-infrared (MIR) laser performances of Er:YAP crystal in this Letter. Under an absorbed pump power of 5.5 W, a maximum CW Er:YAP laser output power of 1.02 W is obtained, corresponding to a slope efficiency of 25.3%. With multilayer ReSe2 material as a saturable absorber, a stable Q-switched Er: YAP crystal laser with dual-wavelength output of 2.73 and 2.80 mu m is realized for the first time, to the best of our knowledge. The nonlinear optical measurements of the multilayer ReSe2 reveal efficient saturable absorption properties around 3 mu m showing a modulation depth of 7.5% and a saturation intensity of 14.5 mu J/cm(2). The maximum Q-switching output power reaches 526 mW, and the corresponding laser power jitter is around 3% in 1 h. The shortest pulse duration and the highest pulse repetition rate are 202.8 ns and 244.6 kHz, respectively. These results prove that Er:YAP crystal could be a reliable laser crystal for MIR solid-state lasers. (C) 2019 Optical Society of America