Above 45 W thermal lens compensated acousto-optically Q-switched Tm:YAP laser.

We demonstrate a high-power Q-switched 2 μm laser with a thermal lens compensated cavity to address severe thermal lens of the Tm:YAP crystal. Robustness of the cavity design, exhibiting long thermal stable region and a broad tolerance to deviations in cavity length is verified by linear power curves at various pulse repetition frequencies in the acousto-optically Q-switching scheme, where maximum average output power of 45.8 W at 1937nm, with a pulse duration of 64 ns is obtained at a pulse repetition frequency of 20 kHz. To the best of our knowledge, this is the maximum nanosecond Q-switched laser power of solid-state Tm lasers, which provides an effective pathway to achieve high-power Q-switching in quasi three-level Er, Tm, or Yb lasers and facilitates the scenarios such as lidar, surgeries and polymer processing that require an accessible high-repetition-frequency pulsed 2 μm laser source.