WS₂ as a saturable absorber for Q-switched 2 micron lasers.

We prepared WS₂ nanosheets by using the thermal decomposition method and demonstrated for the first time its nonlinear saturable absorption property at around 2 μm. With the as-prepared WS₂ nanosheets as saturable absorber (SA), a passively Q-switched Tm:LuAG laser was realized successfully, and 660 ns laser pulses with an average output power of 1.08 W and pulse peak power of 26 W at a repetition rate of 63 kHz were obtained for an incident pump power of 7 W. Our experimental results definitely demonstrate that WS₂ could be a kind of promising SA for solid-state 2 μm lasers.