Switchable and tunable single-longitudinal-mode dual-wavelength Ho:YLF laser based on different wavelength combinations

A switchable and tunable Ho:YLF laser operating in both single- and dual-wavelength single-longitudinal-mode regimes is demonstrated. An uncoated fused quartz etalon with a thickness of 1 mm and a 6-mm-thick quartz etalon coated with 20% reflectivity are used to suppress multi-longitudinal modes. The maximum output power for single-longitudinal-mode operation is 360 mW with the wavelength of 2063.10 nm. The switching of single- and dual-wavelength at different wavelength combinations is realized by rotating the thin film polarizer (TFP) perpendicular to the optical axis. By rotating the TFP angle from -13.4° to 17.7°, the output of single-wavelength emission (at 2050nm and 2064nm) and dual-wavelength emission (within the 2050nm band, the 2064nm band, and a hybrid of both) is achieved. The calculated beam quality M² and power stability of the Ho:YLF laser are 1.34 and 1.77%, respectively.