电子束蒸发制备平板偏振膜激光损伤特性研究

采用电子束蒸发沉积技术制备了平板偏振膜。用Lambda900分光光度计测试了其光学性能。在中心波长1053 nm处P偏振光的透过率TP>98%,S偏振光的透过率TS<0.5%,消光比TP/TS>200∶1,带宽约为20 nm。用波长1064 nm,脉宽12 ns的脉冲激光进行损伤阈值测试,获得P偏振光的损伤阈值为17.2 J/cm2,S偏振光的损伤阈值为19.6 J/cm2。用Nomarski显微镜对薄膜的损伤形貌进行观察,并用Alpha-500型台阶仪对损伤深度进行测试。结果表明,P偏振光的激光损伤为界面损伤与缺陷损伤,而S偏振光的激光损伤主要是驻波电场引起的界面损伤,界面损伤发生在偏振膜表面第一层与第二层界面处,缺陷损伤发生在偏振膜内部。

Laser-Induced Damage of Flat Polarizer Prepared by Electron Beam Evaporation

The flat polarizer was prepared by electron beam evaporation and its optical performance was measured by Lambda900 spectrometer. The transmission of P-polarization is more than 98%, the transmission of S-polarization is less than 0.5%, its extinction ratio is more than 200:1, and its spectral bandwidth is 20 nm near 1053 nm. The laser-induced damage thresholds (LIDTs) of P-polarization and S-polarization are 17.2 J/cm2 and 19.6 J/ cm2, respectively, measured at 1064 nm wavelength,12-ns pulse width and the incident angle of 60°. The morphology of the laser-induced damage was characterized by Nomarski microscopy and its depth was measured by Alpha-500 step meter. Two distinct damage morphologies (defect and delamination) were observed when polarizer was tested in P-polarization. The character of interface caused the outer layer delamination damage morphology and which happened at hafnia-silica interface of the outer layer. The defect damage was induced by the defects in the film, and it appeared in the interior of the polarizer. In the case of S-polarization,the outer layer delamination damage morphology,which was induced by standing electric field was also observed.