Pulsed Tm:Ca(Gd,Lu)AlO4 laser doubly Q-switched by acousto-optic modulator and CVD-grown tungsten disulfide (WS2)

A two-dimensional WS2 grown by chemical vapor deposition (CVD) is employed as saturable absorber. Using a novel crystal of Tm:Ca(Gd,Lu)AlO4, doubly Q-switched laser with acousto-optic modulator (AOM) and WS2 saturable absorber is presented. The shortest pulse width of 91 ns corresponding to a highest peak power of 1.2 kW is obtained when the modulation rate (MR) of AOM is 1 kHz. In comparison to the singly Q-switched lasers with WS2 or AOM, the maximum pulse width compression ratio is 15.38 and the highest peak power enhancement factor is 511.30. The experiment results show a promising saturable absorption of WS2 and that the doubly Q-switched laser is beneficial for compressing the pulse width and improving the peak power.