为了得到一种三倍频效率高达60%的355 nm脉冲激光器, 采用曲率半径分别为2 m的凹凸高斯镜和9 m的平凹全反镜组合作为谐振腔, 加以电光调Q, 得到1 064 nm高光束质量激光输出, 再将其进行行波放大, 获得重复频率10 Hz、脉宽7.3 ns、单脉冲能量1.01 J的1 064 nm基频光输出。利用 Ⅰ 类相位匹配LBO晶体进行二倍频、 Ⅱ 类相位匹配LBO晶体进行三倍频以得到波长为355 nm的紫外光输出。通过二倍频和三倍频输出特性和非线性晶体参数的分析和实验调试, 最终获得了单脉冲能量为608 mJ、脉宽为5.7 ns、线宽为2 nm的紫外激光输出。通过优化二倍频的转换效率, 可使1 064 nm基频光到三倍频得到的355 nm紫外光的转换效率达60%。

In order to obtain a 355 nm pulsed laser with a triple frequency efficiency up to 60%, the combination of Gaussian mirror and plano-concave reflection mirror is used as laser resonance cavity. The Gaussian mirror is a convexo-concave mirror, the radius(r) of curvature is 2 m. The radius of curvature of the plano-concave reflection mirror is 9 m. Through the electro-optically Q-switched, 1 064 nm laser output is obtaimed. Then the 1 064 nm local oscillator is amplified by traveling wave, 1 064 nm fundamental frequency light of single pulse energy 1.01 J is obtained, the repetition frequency is 10 Hz and the pulse width is 7.3 ns. The class Ⅰ phase-matched LBO crystal is used for SHG and the class Ⅱ phase-matched LBO crystal is used for SFG to obtain 355 nm ultraviolet laser output. Through the analysis of the output characteristics and nonlinear crystal parameters of the second harmonic and third harmonic, and experiments, finally the 355 nm UV laser output is achieved that the single-pulse energy is 608 mJ, the pulse width is 5.7 ns and the line width is 2 nm. Through optimizing the conversion efficiency of double frequency, the conversion efficiency of 355 nm UV light got by the processing SFG from 1 064 nm fundamental light reaches 60%.