Cr:ZnS saturable absorber passively Q-switched Tm,Ho:GdVO₄ laser

A passively Q-switched Tm,Ho:GdVO₄ laser operating at cryogenic temperature with a Cr²⁺:ZnS saturable absorber pumped with continuous wave LDs was demonstrated. The performance of the laser was investigated through changing the distance between Cr²⁺:ZnS and output coupler. The maximum pulse energy of 70.5 μJ was obtained at 10 W input power. The maximum average output power of PQS laser was up to 3.2 W at the pump power of 22.8 W, corresponding to CW output power of 7.4 W, pulse repetition frequency of 52 kHz, and a pulse width of 389 ns. The M² factor measured by the traveling knife-edge method was ∼1.1 in x and y directions with near-diffraction limited beam quality.