La2CaB10O19(LCB)为可通过Nd∶YAG激光三倍频产生355 nm紫外激光的非线性光学晶体, 其光学性能可与商用化的LiB3O5 (LBO)晶体媲美, 但抗潮解特性优势明显。本文对用LCB晶体实现355 nm紫外激光输出的三倍频产生过程进行了优化设计, 利用走离补偿方法来提高激光输出转换效率。通过在光路中加入沿θ=45°方向切割、厚度为1.2 mm的方解石晶体走离补偿片, 在脉冲宽度为60 ns、重复频率10 kHz的激光参数下实现355 nm输出功率由12 W提升至20 W; 在脉冲宽度为25 ps、重复频率为10 Hz的激光参数下355 nm转换效率由28.3%提升至35.2%。

La₂CaB₁₀O₁₉(LCB) is a nonlinear crystal which can produce 355 nm ultraviolet (UV) laser output through the third harmonic generation (THG) of Nd∶YAG laser, its optical property is comparable to that of commercial LiB3O5(LBO) crystal, with an obvious advantage in its moisture resistance. In this paper, the THG process of 355 nm UV laser output with LCB crystal was optimized, and the walk-off compensating method was used to improve the conversion efficiency of laser output. By adding a calcite crystal compensator cut at θ=45° to the optical axis with a thickness of 1.2 mm, the output power of 355 nm can be increased from 12 W to 20 W under the laser parameters of 60 ns pulse width and 10 kHz repetition rate. When the pulse width is 25 ps and the repetition rate is 10 Hz, the conversion efficiency from 1 064 nm to 355 nm is improved from 28.3% to 35.2%.