介绍了激光二极管(LD)侧面抽运Nd:YAG晶体腔外四倍频获得平均功率为1.85 W的266 nm全固态紫外激光器。采用双棒串接结构, 对热致双折射作用引起的退偏效应进行补偿, 获得高光束质量、高稳定性的线偏振1064 nm基频光输出。分别采用Ⅰ类非临界相位匹配的三硼酸锂(LBO), Ⅰ类相位匹配的β相偏硼酸钡(BBO)作为腔外倍频和四倍频晶体, 获得了平均功率1.85 W, 脉冲重复频率10 kHz和转换效率达13.3%的紫外激光输出。同时研究了BBO晶体自热效应对四倍频相位匹配角的影响, 提出了可以通过调整BBO晶体的角度来减小自热效应的影响。

An 1.85 W laser diode (LD)-side-pumped Nd:YAG extra-cavity fourth harmonic generation (FHG) all-solid-state 266 nm ultraviolet laser is reported. The high-beam-quality high-stability linear-polarized 1064 nm fundamental frequency laser is obtained from thermal-induced birefringence-compensated resonator with two Nd:YAG rods. The type-Ⅰnoncritical phase-matched LBO and type-Ⅰphase-matched BBO crystals are used as the extra-cavity frequency doubled and FHG crystal respectively. 1.85 W ultraviolet laser of 266 nm is obtained at the pulse repetition rate of 10 kHz with the conversion efficiency of 13.3% from green to ultraviolet light. The self-heating effect of BBO crystal on FHG phase-matched angle is studied, and the result that the self-heating effect can be reduced by adjusting the angle of BBO is proposed.