946 nm Nd: YAG double Q-switched laser based on monolayer WSe₂ saturable absorber

In this paper, we report a 946nm double Q-switched laser side pumped by an 808-nm pulse laser diode (LD). A layered tungsten diselenide (WSe₂) saturable absorber (SA) together with an MgO doped LiNbO₃ electro-optic (EO) modulator is applied to double Q-switch the Nd: YAG laser, producing trains of nanosecond-duration pulses with 500 Hz repetition rate. Such WSe₂ saturable absorbers are fabricated by chemical vapor deposition (CVD) in a hot wall chamber and then embedded into a resonant mirror. The achieved pulse energy of double Q-switched laser at 946 nm is approximately 2.63 mJ with 10.8 ns pulse width and the peak power is round 244 kW, corresponding to the beam quality factors of M²_x = 3.846,M²_y = 3.861. Monolayer WSe₂ nanosheets applied in the experiment would be a promising SA for passive Q-switching operation.