Sub-nanosecond KTP-OPO pumped by a hybrid Q-switched laser with WS_2 saturable absorber and AOM

Abstract

By using a few-layered tungsten disulfide (WS2) nanosheet based saturable absorber (SA) prepared with the ultrasonic assisted vertical evaporation method, a diode-pumped singly Q-switched laser is demonstrated. At an incident pump power of 6.54 W, a maximum output power of 1.18 W with a minimum pulse duration of 53 ns is obtained from the singly WS2-SA Q-switched laser. To the best of our knowledge, this is the shortest pulse duration ever achieved from a diode-pumped solid-state passively Q-switched laser with a WS2-SA at 1.06 μm. Based on this, a sub-nanosecond KTiOPO4 (KTP) based intracavity optical parametric oscillation (IOPO) pumped by a hybrid Q-switched laser with a WS2-SA and an acousto-optic modulator (AOM) is realized. At an incident pump power of 10.2 W and an AOM repetition rate of 10 kHz, a maximum output power of 233 mW with a minimum pulse duration of 810 ps for signal wave is obtained. The experimental results indicate that the IOPO pumped by the hybrid Q-switched laser with an AOM and a WS2-SA can generate a signal wave with a shorter pulse duration and a higher peak power than that pumped by the Q-switched laser with an AOM and a graphene-SA or a molybdenum disulfide SA (MoS2-SA).