Doubly Q-switched Tm:YAP laser with g-C3N4 saturable absorber and AOM

Abstract Two-dimensional (2D) graphitic carbon nitride (g-C3N4) was fabricated as saturable absorber (SA) and the nonlinear optical absorption properties were measured. A laser-diode (LD) pumped doubly Q-switched Tm-doped yttrium-aluminium perovskite YAlO3 (Tm:YAP) laser at 2 μm with g-C3N4 and acousto-optic modulator (AOM) is presented for the first time to the best of our knowledge. Under an absorbed pump power of 5.34 W, the minimum pulse width of 239 ns and the maximum peak power of 1146 W were obtained by the doubly Q-switched laser. In comparison with the singly Q-switched laser using g-C3N4 SA or AOM, the dual-loss-modulated Q-switched laser could generate shorter pulse width and higher peak power. The maximum pulse width compression ratio was 4.48 and the highest peak power enhancement factor was 241. The experimental results indicated that 2D g-C3N4 SA is potential in Q-switched laser at 2 μm and the doubly Q-switched technology is a useful way to compress the pulse width and improve the peak power.