膜基结构是超材料和柔性电子设备等光电子器件的基础结构。建立有效的实验手段对膜基结构进行应力分析，对于这些光电子器件的研究与设计有非常重要的意义。本项目的前期研究表明虽然太赫兹脉冲照射金属薄膜时大部分能量被反射或吸收，但透射的微弱信号可以被太赫兹时域光谱系统准确探测。本项目拟以上述特性为基础，改进现有太赫兹时域光谱系统，构建一个薄膜应力分析系统。拟重点从如下四个方面开展研究：1）建立双臂太赫兹时域光谱差分系统，实现膜、基内部应力的分离；2）研究金属薄膜的应力光学效应，为应力分析奠定理论基础； 3）研究薄膜应力在上述双臂系统中的光谱传递模式，并建立相应的算法实现应力参量的分离与提取；4）探寻对系统时间分辨率有重要影响的关键因素，并建立相应的误差传递模型，为进一步提高系统的时间分辨率奠定基础。最后，综合利用上述技术，建立可用于探测薄膜内应力信息的高精度的双臂太赫兹时域光谱差分系统。

The film-substrate system is the basic structure of some optoelectronic devices such as metamaterials and flexible electronic devices. It is of great significance for the research and design of these optoelectronic devices to establish an effective experimental method for the stress analysis for film-substrate system. The preliminary study of this project shows that although most of the energy is reflected and absorbed when a terahertz plus is projected on a metal film, the weaken signal can be accurately detected by THz time-domain spectroscopy system. On the basis of the mentioned phenomenon, this project proposes an improved terahertz time-domain spectroscopy system to construct system to analyze the stress in thin film. The projected will carry out the research from four aspects as follows. Firstly, a terahertz time-domain spectrum difference system with double probing arms will be established to separate stresses in thin film and substrate. Secondly, stress optical effects of metal films will be investigated so that a theoretical basis can be laid of stress analysis according to the obtained spectrum information. Thirdly, the relationship between the transmission spectrum and the undergone stresses will be researched so that an algorithm can be established to obtain the stress parameters. At last, we will to explore the key factors which have important effect on the time resolution of the established system, and establish the corresponding error propagation model, which lays the foundation for further improving the time resolution of the system. Based on the mentioned techniques, a high accuracy dual-arm terahertz time-domain spectral difference system can be established to detect the stress information of the thin films.