Compact passively Q-switched Tm:YLF laser with a polycrystalline Cr:ZnS saturable absorber

•A compact and simple plano-concave resonant cavity was first employed for passively Q-switched Tm:YLF laser.•The highest average output power of 478 mW was obtained for passively Q-switched Tm:YLF laser up to now.•A higher repetition rate of 378 Hz was obtained for passively Q-switched Tm:YLF laser.

A compact passively Q-switched diode-pumped Tm:YLF laser with polycrystalline Cr:ZnS as the saturable absorber is demonstrated. In the Q-switching regime, the maximum average output power reached 478 mW with the incident pump power of 16 W, which is the highest average output power for PQS Tm:YLF laser up to now. The maximum pulse energy of 529 μJ was obtained with 8.96 kW peak power and 59 ns pulse duration near 1.9 μm, respectively.