双反射薄膜的设计和实现

Design and implementation of bireflectance film

弹光效应双反射膜是一种各向异性的高反射膜。在预加了应力的基片上镀制高反射膜 ,然后撤去基片上的预加应力 ,则基片上因弹性变形而产生的应变便转移到了膜系上。由于弹光效应使膜系成为各向异性的 ,从而使垂直入射光束的两个正交偏振反射分量有了一定的相对相位延迟。理论分析和实验证明 ,选择好膜系结构 ,确定好中心波长 ,并经优化 ,在工作波长处可以得到较大的相位色散 ,施加 10 0 N的力就能在正交方向获得 1.8°的相位差而反射率保持不变 ;此膜系用于氦氖激光器 ,可制出频差为 5 MHz量级的双频激光器。文中给出了一个弹光效应的双反射膜的结构参数和数值计算结果。

Bireflectance film based on the photoelastic effect is a kind of anisotropic high reflection coating. Coating high reflectance film on the substrate pre applied stress and then remove the stress, the strain of the substrate caused by elastic deformation can be transferred to the film series. The film series becomes anisotropic due to the phtoelastic effect, therefore a relative phase delay is brought out between the two orthogonal polarized reflective components of the mormal incident light. Theoretical analysis and experiments have proved that selecting suitable film series structure, determining appropriate center wavelength and being optimized can get large phase dispersion at working wavelength. Furthermore, orthogonal phase difference of 1.8° can be obtained by applying a force of 100N while reflective index is almost not varied. If this film series is used in He Ne laser, the dual frequency laser with 5MHz beat will be produced. The structural parameters and numerical calculation results of a bireflectance film of the photoelastic effect are presented.