详细调研了近年来基于光纤激光倍频的高功率绿光光源的研究进展，绿光激光功率从百瓦到千瓦，光束质量近衍射极限，而且输出功率有望进一步提升。采用光纤激光倍频技术得到高功率绿光光源的技术路线大致分为两条：一条是用高功率单子束光纤激光器作为基频光源，然后级联单程非临界相位匹配LBO晶体作为倍频；另一条是用多子束光纤激光器作为基频光源，然后合成与倍频分别实现，或者合成与倍频一体实现。对比两条技术路线，前者相对后者简单，后者具有更高输出功率的潜力，但是倍频晶体的弱吸收是两条技术路线共同面临的问题。

Fifth harmonic generation (5th HG) of a Nd:glass laser is an effective way to acquire high-energy coherent deep-ultraviolet radiation near 200 nm. In this work, cascade generation of the fifth harmonic of a Nd:glass laser in a 5 mm ammonium dihydrogen phosphate (ADP) crystal was investigated, and maximum conversion efficiency of 14% and large angular acceptance of 45 mrad were demonstrated at a noncritical phase-matching temperature of 75.1°C. However, as the results reveal, the temperature sensitivity and nonlinear absorption would hinder its high-energy application. As for that, based on the complementary relationship of the angle and temperature in the phase-matching condition, an upgraded focusing 5th HG design coupled with the cylindrical temperature distribution scheme was proposed. By this upgraded focusing design, more than the improvement of the conversion efficiency, the output 5ω near-field intensity distribution turns out to be insensitive to the temperature gradient. Potentially, this idea can be applied for many other frequency conversion schemes such as high-repetition frequency lasers, which have similar temperature gradient problems.