为了解决光纤式太赫兹时域频谱系统中光学延迟线部分的延迟精度和耦合效率低的问题,提出了两种延迟线设计方案,保证延迟线光路的可行性。两种方案设计原理简单且成本低。分别由光纤激光器、准直器、四分之一波片以及金膜平面反射镜构成的光学系统和由光纤激光器、准直器以及直角棱镜构成的光学系统,介绍了延迟线整体的构成和基本原理。同时,根据项目的具体要求,关键光学器件主要适用于1 550 nm的波长。在设计出光学延迟线以后,搭建光学系统,并对整个光路进行了测试和验证。实验结果表明：第一种方案较第二种方案耦合效率高,但第二种方案延迟精度高,稳定性好且可操作性强。

In order to solve the problem of delay precision and low coupling efficiency of optical delay line in optical fiber terahertz time domain spectrum system, two delay line design schemes are proposed to ensure the feasibility of the delay line optical path. The two schemes are simple in design and low in cost. One optical system is composed of fiber laser, collimator, a quarter wave plate and gold-film plane mirror, and the other is composed of fiber laser, collimator and right angle prism. Then the Constitution and basic principle of the delay line are introduced. At the same time, according to the specific requirements of the project, the key optical devices are mainly applicable to the wavelength of 1 550 nm. After the optical delay line is designed, the optical system is built, and the whole optical path is tested and verified. The experimental results show that the first scheme has higher coupling efficiency compared with the second schemes, but the second scheme has high delay precision, good stability and strong operability.