Pulse lasers based on WS₂ saturable absorber

Based on the saturable absorption characteristics of WS₂, passively Q-switching and passively Q-switched mode locking operations of a side-pumped Nd:YAG solid-state laser were experimentally demonstrated in a self-designed Z-type four-mirror cavity structure. The Q-switching operation started under the pump current of 9.5 A and turned into a stable operation under more than 9.8 A. When the pump current was 12.8 A, the maximum average output power was 466 mW, the narrowest pulse width was 3.205 μs, the repetition frequency was 71.70 KHz, corresponding to the maximum pulse energy of 6.5 μJ.When the pump current was 13.4 A, a passively Q-switched mode locking operation was obtained. The maximum output power of passively Q-switched mode locking was 590 mW, the repetition rate of Q-switched pulse was 71.98 KHz, and the corresponding repetition rate of pulse train under single Q-switched pulse envelope was 123.1 MHz, and each Q-switched envelope contained 369 pulses with the single pulse energy of 22.2 n.The results show that the WS₂ material can act as the absorber for solid-state lasers.