Efficient continuous-wave and passively Q-switched operation of an Yb: YPO₄ microchip laser

We report on the performance of an Yb:YPO4 microchip laser that could be efficiently operated in both continuous-wave (CW) and passive Q-switching mode, with a 2D WS2 acting as the saturable absorber. With 6.30 W of pump power absorbed, a CW output power of 3.81 W was generated, leading to an optical conversion efficiency of 60.5%, while the slope efficiency amounting to 71%. In passively Q-switched operation, a pulsed output power of 1.67 W was produced at 660 kHz of repetition frequency, with a slope efficiency of 52%; the largest pulse energy, minimum pulse width, and highest peak power, which were achievable with different output mirrors, were respectively 2.52 mu J, 67 ns, and 31.7 W. The results demonstrated in this work represent a significant improvement in CW and passive Q-switching performance of Yb:YPO4 microchip lasers.