Passively Q-switched Tm:YAlO3 laser based on WS2/MoS2 two-dimensional nanosheets at 2 μm

A comparison of the pulsed laser performances of 2 μm passively Q-switched Tm:YAlO3 (YAP) lasers based on the use of tungsten disulfide (WS2) and molybdenum disulfide (MoS2) two-dimensional (2D) nanosheets as saturable absorbers is reported. The novel nanosheets were prepared by chemical vapor deposition (CVD) technology. The microstructure and optical characteristics of the nanosheets were investigated experimentally. In a continuous-wave (CW) operation, the maximum output power of 2.8 W was obtained at an absorbed pump power of 6.9 W, with a corresponding slope efficiency of 46.4%. In a passively Q-switched operation at a pump power of 1.45 W, the average output power, pulse width, repetition rate, pulse energy, and peak power for the Tm:YAP/WS2 laser were 0.11 W, 2.65 μs, 34.7 kHz, 2.9 μJ, and 1.23 W, respectively. As for the Tm:YAP/MoS2 laser, the corresponding values were 0.10 W, 2.5 μs, 24.0 kHz, 3.8 μJ, and 1.55 W.