1 053，527，351 nm倍频分离膜的制备与性能研究

 用电子束蒸发及光电极值监控技术在石英基底上沉积了三倍频分离膜，将部分样品置空气中于250 ℃温度下进行3 h热退火处理。然后用Lambda900分光光度计测量了样品的光谱性能；用表面热透镜技术测量了样品的弱吸收值；用调Q脉冲激光装置测试了样品分别在355 nm和1 064 nm的抗激光损伤阈值。实验结果发现，样品的实验光谱性能良好，退火前后其光谱性能几乎没有发生温漂，说明薄膜的温度稳定性好；同时弱吸收平均值从退火前的1.07×10^-4下降到退火后的6.2×10^-5，从而使对基频的抗激光损伤阈值提高，从14.6 J/cm²上升到18.8 J/cm²，但是三倍频阈值在退火后有显著降低，从7.5 J/cm²下降到2.5 J/cm²。

Fabrication and properties of third harmonic beam splitter

Third harmonic beam splitter at 355 nm was deposited on silica substrates by electron beam evaporation and photoelectric maximum control method. Part of the samples were annealed in air at 250 ℃ for 3 hours. The optical transmittance of samples was measured by spectrometer LAMBDA900, the weak absorption of coatings was characterized with surface thermal lensing technique (STL), and the laser induced damage threshold (LIDT) of coatings assessed using 355 nm Q-switch pulsed laser at a pulse length of 7 ns. It was found that the samples had good spectrum performance before and after annealing. After annealing the LIDT of the samples at 1 064 nm increased remarkably from 14.6 J/cm2 to 18.8 J/cm2 with the decreasing of absorption from 1.07×10-4 to 6.2×10-5, but the LIDT at 355 nm decreased o