高效率高功率全固态紫外激光器

High Efficiency and High Power All-Solid-State Ultraviolet Laser

报道了采用大功率国产光纤束模块端面抽运Nd∶YVO4激光晶体的腔外三倍频紫外激光器,用声光调Q技术实现了高功率高光束质量基频光输出。采用LBOⅠ类相位匹配和LBOⅡ类相位匹配的腔外倍频方法,并利用凹面反射镜的方式进行聚焦,避免了1064nm和532nm激光聚焦时由于波长的不同而产生的色差效应,有效地提高了三倍频的倍频效率。最终在注入抽运光功率为23.3W,声光调Q激光器的调制频率为20kHz的工作条件下,基频光输出功率为7.28W时,得到紫外激光输出功率为1.86W,1064nm基频光到355nm紫外激光的光-光转换效率为25.5%,此外,对紫外激光光束质量的测试表明,该紫外激光器具有高功率输出的同时仍有很好的光束质量。

A high power end-pumped Nd： YVO4 all-solid-state ultraviolet （UV） laser was demonstrated under acousto-optic Q-switched operation, using type Ⅰ phase-matched LiB305 （LBO） as second harmonic generation （SHG） crystal and type Ⅱ phase-matched LBO as third harmonic generation （THG） crystal. To improve the optical to optical （O-O） efficiency of fundamental wave to THG UV laser, a concave reflection mirror is used to focus the laser into THG LBO crystal, which avoids the chromatic aberration of traditional focusing lens effectively. Finally, the output power of 355 nm UV laser reaches to 1.86 W at the incident pump power of 23.3 W, and the output power of fundamental wave is about 7.28 W at 20 kHz repetition rate, and O-O conversion efficiency is about 25.5 % accordingly. The test results of UV laser beam quality indicate that the laser can still work at a good beam quality even at the maximum output, which means that the UV laser can have a very good beam quality even at the high power output.