Diode-pumped, 2-micron, q-switched tm:YAG microchip laser

In this report we discuss the design, simulation, construction, and characterization of an actively Q-switched, diode-pumped solid state laser operating at 2 μm. The laser cavity has a microchip configuration and uses a 6% thulium-doped YAG crystal as the lasing medium. In continuous wave mode, we achieve output powers of up to 450 mW with a slope efficiency of 9.5%. Using an acousto-optic Q-switch, the laser was run in pulsed mode at an average power of 42 mW and a pulse rate of 1.66 kHz. Pulse duration was approximately 400 ns with a pulse energy of 25 μJ. The center wavelength was 2.019 μm with a linewidth of \u3c0.045 nm. Additionally, a design is presented for replacing the active Q-switch with a chromium-doped zinc selenide crystal acting as a saturable absorber passive Q-switch. Finally, we will propose possible future modifications to the laser system design to improve its performance, ruggedness and compactness, and to broaden its functionality