1.5-MHz repetition rate passively Q-switched Nd: YVO₄ laser based on WS₂ saturable absorber

A transmission-type tungsten disulfide (WS₂)-based saturable absorber (SA) is fabricated and applied to passively Q-switched Nd:YVO₄ laser. The WS₂ nanosheets are deposited on a quartz substrate by the vertical evaporation method. By inserting the WS₂ SA into the plano-concave laser cavity, we achieve 153-ns pulses with an average output power of 1.19 W at 1064 nm. To the best of our knowledge, both of them are the best results among those obtained by the Q-switched solid-state lasers with WS₂-based absorbers. The repetition rate ranges from 1.176 MHz to 1.578 MHz. As far as we know, it is the first time that MHz level Q-switched pulses have been generated in all solid state lasers based on low-dimensional materials so far.