单层膜体吸收与界面吸收研究

Volume and interface absorptions of single layer

采用热透镜测量方法进行了SiO2和HfO2单层膜的体吸收与界面吸收分离研究.首先推导了光从薄膜侧及基底侧入射时单层膜内的驻波场分布,给出了单一厚度薄膜分离体吸收和界面吸收的计算方程式以及求解薄膜消光系数的方法.利用电子束蒸发工艺制备了半波长光学厚度(λ=1064nm)的SiO2和HfO2单层膜,通过热透镜的测量数据实际分离了两种薄膜的体吸收和界面总吸收.计算结果表明,对于吸收小至10-6量级的薄膜来说,薄膜的界面吸收相对于体吸收不可忽略;制备HfO2薄膜的体吸收和界面吸收都比SiO2薄膜大.

The volume absorptions and the interface absorptions of SiO2 and HfO2 single layers are studied using the thermal lens method.Based on the fact that electric field distributions in single layers are different when the films are illuminated from the coating side and substrate side,an equation is given to calculate volume and interface absorptions of single layers.Half wave HfO2 and SiO2 single layers are prepared by electron beam evaporation method.With the absorption data measured by thermal lens technique,we separate the volume absoption from the interface absorption for these two single layers.The results show that interface absorption is non negligible when the absorption of film approaches to a ppm level.Additionally,the HfO2 single layer shows bigger volume and interface absorptions than SiO2 single layer.