Passively Q-switched dual-wavelength Yb:LSO laser based on tungsten disulphide saturable absorber

We demonstrate a passively Q-switched Yb:LSO laser based on tungsten disulphide(WS_2) saturable absorber operating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS_2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 μs with a repetition rate of 76.9 k Hz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 m W, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS_2 nanoplatelets.