Output characteristics of an actively Q-switched Tm:GdScO₃ slab laser at 2 μm band

Abstract An acousto-optic Q-switched Tm:GdScO 3 slab laser at different pulse repetition frequencies was successfully demonstrated for the first time. The size of a slab crystal doped with a 2 at% Tm 3+ is 2 mm × 4 mm × 20 mm. With the pump power of 33 W, a maximum average output power of 3.03 W was obtained with center wavelength of 1980 nm at pulse repetition frequency of 20 kHz. The optical-to-optical conversion efficiency and slope efficiency were 9.18% and 16.66%, respectively. The maximum pulse energy was 0.60 mJ with pulse width of 160 ns at 1 kHz, corresponding to the peak power of 3.75 kW. In addition, at the pump power of 33 W, the beam quality factors M 2 for horizontal and vertical directions were 1.33 and 1.08, respectively.