Dual-wavelength passively Q-switched Nd:GYSGG laser by tungsten disulfide saturable absorber

A dual-wavelength passively Q-switched Nd:GYSGG laser using vacuum evaporating tungsten disulfide (WS_2) as a saturable absorber was demonstrated for the first time to the best of our knowledge. The WS_2 saturable absorber was prepared simply by evaporating nanometer WS_2 powders onto a quartz substrate in a vacuum. By inserting the WS_2 saturable absorber into the laser cavity, stable Q-switched laser operation was achieved with a maximum average output power of 367 mW, a pulse repetition rate of 70.7 kHz, the shortest pulse width of 591 ns, and pulse energy of about 1.05 μJ. By vacuum evaporation method, a high-quality WS_2 saturable absorber can be produced, and it seems to be a suitable method for fabrication of 2D transition metal dichalcogenides.