Repetition-frequency-controllable double Q-switched Ho:LuAG laser with acousto-optic modulator and Cr2+:ZnS saturable absorber

A repetition-frequency-controllable double Q-switched (DQS) Ho:LuAG laser at 2098.34 nm with acousto-optic modulator (AOM) and Cr2+:ZnS saturable absorber (SA) was investigated. The maximum output power of 5.3 W was obtained at the AOM repetition frequency (RF) of 3.72 kHz, corresponding to the slope efficiency of 29.8%. The largest pulse energy of 2.8 mJ with the shortest pulse width of 54.2 ns was observed at the AOM RF of 2.64 kHz. Compared with the passively Q-switched Ho:LuAG laser, the DQS Ho:LuAG laser could generate shorter pulse width and larger pulse energy, and its RF could be controlled by the AOM RF.