Passive Q-switching of a Tm,Ho:KLu(WO_4)_2 microchip laser by a Cr:ZnS saturable absorber

A diode-pumped $\mathrm{Tm},\mathrm{Ho}\text{:}\mathrm{KLu}{({\mathrm{WO}}_4)}_2$ microchip laser passively $Q$-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a $Q$-switching conversion efficiency of 58%. The pulse characteristics were $14\mathrm{ns}/9\mathrm{\mu J}$ at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, $9\mathrm{ns}/10.4\mathrm{\mu J}/8.2\mathrm{kHz}$ pulses were generated at 2061.1 nm, corresponding to a record peak power extracted from a passively $Q$-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented, predicting the pulse energy and duration. The simulations are in good agreement with the experimental results.