High-efficiency 261-nm continuous-wave laser by single-blue-laser-diode-pumped Pr³⁺:LiYF4 crystal

High-power continuous-wave (CW) deep ultraviolet lasers attract growing research interest in the field of optoelectronics. Herein, we perform a CW deep ultraviolet laser at 261 nm by the intracavity frequency doubling of a single-blue-laser-diode-pumped Pr3+:LiYF4 (Pr:YLF) laser. The excellent mode matching between the pump and fundamental-frequency laser beams is realized by optimizing the pump focusing and laser resonator systems. On that basis, the maximum CW fundamental-frequency laser obtained is 1.41 W at 522 nm, corresponding to a slope efficiency of 59.12%. Moreover, a deep ultraviolet laser is further demonstrated at 261 nm using a beta-BaB2O4 (BBO) frequency-doubling crystal, yielding a maximum output power of 1.17 W and an optical-optical conversion efficiency of 33.4% with respect to the pump power. Such a result is the highest optical-optical conversion efficiency of the CW DUV lasers from Pr3+-doped crystals, to the best of our knowledge. The finding in this work manifests the development potential of all-solid-state deep ultraviolet lasers and provides a feasible avenue for achieving high-efficiency deep ultraviolet laser output.