Towards Power Scaling of Simple CW Ultraviolet via Pr: LiYF₄-LBO Laser at 320 nm

Intracavity frequency doubling of diode-pumped continuous-wave Pr ³⁺ laser in visible spectral region is a highly efficent and cost-effective method for the generation of high-performance continuous-wave ultraviolet laser. However, to date, diode-pumped continuous-wave frequency doubled Pr ³⁺ -based ultraviolet laser has still been power limited only to about one watt. In this work, employing two 12-W blue diode lasers as pump sources individually, we achieved maximum output powers up to 1.82 W and 1.73 W of ultraviolet lasers at about 320 nm by intracavity frequency doubling of continuous-wave Pr:LiYF ₄ (YLF) lasers at 640 nm. The used nonlinear frequency doubler is a 12-mm LBO crystal. For further power scaling of the ultraviolet laser, a total pump power of 24 W was injected into the laser crystal by configuring a double end pumping geometry. Under this situation, a maximum output power of 3.22 W can be achieved, which is believed to be the highest continuous-wave ultraviolet laser via intracavity frequency doubling. This solid-state 320-nm ultraviolet laser could replace the relatively cumbersome He-Cd vapor laser for a variety of applications.