Efficient Passively Q-Switched Nd:YAG/Cr⁴⁺:YAG/LBO Microchip Laser

Performance of an LD-end-pumped passively Q-switched Nd:YAG/Cr⁴⁺:YAG microchip laser operating at 1123 nm is studied. A maximum average output power of 517 mW with an optical-to-optical conversion efficiency of 12.6% and a slope efficiency of 25.8% is obtained under a pump power of 4.1 W. A minimum pulse width of 1.1 ns with a pulse repetition rate of 20.2 kHz is obtained, and the corresponding pulse energy and peak power are 25.6 μJ and 23.3 kW, respectively. To our knowledge, the 23.3 kW peak power is the highest among 1123 nm lasers. Additionally, based on the 1123 nm laser, with LBO as the frequency doubler, a 288-mW green-yellow laser at 561 nm is successfully achieved.