KTP晶体环形腔外腔倍频Nd∶YAG激光光束特性的研究

Study of Beam Quality and Focus of Frequency Doubling in a KTP Crystal on Nd∶YAG Laser by the Resonant External Ring Cavity

为了解决精细聚焦问题,采用Nd∶YAG倍频技术以获得短波长激光器。在激光烧结技术、获取短波长激光的方法、短波长激光光束特性等方面进行了研究和探讨。从理论和实验两方面,研究了利用KTP晶体对Nd∶YAG激光进行环形腔外腔倍频的方法。这种倍频所利用的基频光最大平均功率为50W,采用声光调Q技术,频率约为1005Hz。当基频光平均功率约为35W的情况下,实验中光光转换效率约为314%。利用BEAMCODESYS光束质量分析系统对二次谐波与基波光束质量进行了比较,并比较研究了二次谐波与基波的聚焦特性。实验中测定的二次谐波TEM00模所占比例约为95%。利用短波长可以获取更小聚焦尺寸,可以在激光粉末成型中得到更微小的成型尺寸,展示了二次谐波在微成型方面应用的初步成果。

In order to solve the problem of fine focus in laser assisted microprocessing, a method of Nd∶YAG frequency doubling is adopted to acquire short wave laser. The frequency doubling in a KTP crystal on Nd∶YAG laser is carried out by the resonant external ring cavity. The maximum average power of Nd∶YAG is 50 W with Q switch and its frequency is 1005 Hz. A 0.532 μm green light output with 31.4% light conversion efficiency is obtained when the average input power of 1.064 μm laser is 35 W. The proportion of TEM 00 model in the green light is 95%. This method is proved to be effective to solve the problem of mini focus, especially useful in the application of laser rapid prototyping. The experimental results for the characteristics of ring cavity frequency doubling are analyzed and compared with those of 1.064 μm laser on the beam quality.