Compact, efficient, low-threshold 320 nm continuous-wave ultraviolet laser

This paper reports a compact, efficient, low-threshold continuous-wave 320 nm ultraviolet laser based on a linear cavity with Pr:YLF and LiB3O5 (LBO) crystals. Thermal effects were analyzed via a three-dimensional temperature field model and thermal lens calculations, guiding the selection of crystal parameters that balance pump absorption and heat load. Using a 0.5 at. % doped Pr:YLF crystal of 8 mm length and a 12 mm long LBO crystal, the laser delivers 3.03 W of continuous-wave 320 nm output with a slope efficiency of 35.2% and a threshold power of 60 mW—the highest slope efficiency reported for a CW Pr:YLF laser at this wavelength. The compact linear cavity minimizes length and loss, offering a viable design for future highly integrated ultraviolet lasers using crystal bonding technology.