A 444 nm blue laser diode and a 469 nm blue laser diode, whose maximum pump powers are 1.4 W and 1.5 W, respectively, are used as the pumping source. The two blue laser diodes are fixed in the π polarization direction. A 45° combiner is used to combine the pump light of the two blue laser diodes. An aspherical lens with a focal length of 4 mm is used as a collimator to collimate the pump light emitted by the blue laser diode. A spherical lens with a focal length of 12 mm is used as a focusing lens to focus the pump light emitted by the blue laser diode. The cavity structure of the laser is V-shaped. The Fabry-Perot etalon is used to select a single-longitudinal mode. The Pr∶YLF crystal with a size of 3 mm×3 mm×5 mm and doping concentration (mass fraction) of 0.5% is used as the gain medium. The type-I phase-matched BBO crystal with a size of 3 mm×3 mm×3 mm is used as the frequency-doubling crystal. By optimizing the resonator parameters and the parameters of two Fabry-Perot etalons, the maximum output power of 261 nm single-longitudinal ultraviolet laser is 110 mW when the incident pump power is 2500 mW.
Xinqi Li, Shuangshuang Pu, Na Niu, Wei Dou, Yue Zhao, Ying Liu, Quan Zheng. Development of 261 nm Single-Longitudinal Mode Ultraviolet Laser[J]. Chinese Journal of Lasers, 2022, 49(9): 0901002