Doubly passively Q-switched Tm:YAP laser with MoS2 and WS2 saturable absorbers at 2 μm

Abstract

By simultaneously inserting MoS2 and WS2 saturable absorbers (SAs) into laser resonator, a doubly passively Q-switched Tm:YAP laser at 2 μm was realized. Measurements of the average output power, the pulse width and the pulse repetition frequency (RF) have been undertaken. In comparison to singly Q-switched laser using MoS2 or WS2, the doubly Q-switched laser using both MoS2 and WS2 can generate more stable pulse trains with shorter pulse width and higher peak power. At the absorbed pump power of 6.04 W, the maximum peak power of 22.4 W and the shortest pulse width of 249.4 ns were obtained. While for singly Q-switched laser using MoS2 or WS2, they were 10.7 W, 528.4 ns and 14.4 W, 458.8 ns. The experimental results hit at a conclusion that the doubly passively Q-switched operation is an efficient way to compress the pulse width, improve the peak power and enhance the stability of pulse trains at 2 μm waveband laser.