Design criteria for a wavelength-selectable laser by adjusting birefringence filter temperature for yellow-green adjustable output.

The design criteria of the wavelength-selectable Nd:YAG laser by controlling a birefringence filter (BRF) rotational angle and temperature are explored. Theoretically, the angle and temperature-dependent BRF transmission are applied to the threshold pump power equation to verify the achievable output wavelength. It is found that by using a thicker BRF with a 3.3-mm length instead of the typical <1-mm design, the temperature-varying range can be narrower, which can be controlled by the thermoelectric module. A selectable wavelength at 1077 nm or 1122 nm can then be achieved for further green-yellow selectable output via SHG. The output performance of the Nd:YAG laser with BRF is experimentally verified, where eight emission peaks can be selected. The green-yellow selectable output is finally obtained with SHG by varying the BRF temperature only.