超薄金属膜在太赫兹波段的探测器、反射镜、波导器件以及太赫兹量子级联激光器中得到了广泛应用。超薄金属膜的光学常数不仅是这些器件设计中不可缺少的参数,而且是开发新型光电材料的一个重要依据。文章运用太赫兹差分时域光谱技术对超薄金属铬、镍和钛膜的光学特性研究,获得其在太赫兹波段的折射率和消光系数,并根据菲涅尔公式计算入射介质为高阻GaAs时,GaAs/Metal界面的反射谱,三种金属在0.3～1.5THz的波段范围内的平均反射率均超过80%。研究超薄金属膜在太赫兹波段的反射特性,为设计性能优良的太赫兹辐射源、探测器及太赫兹光学元件奠定基础。 Thin metal films have found wide use in terahertz-band detectors, mirrors, waveguide devices, and terahertz quantum cascade lasers. The optical constants of ultra-thin metal films are not only an indispensable parameter in the design of these devices, but also an important basis for the development of new photoelectric materials. In this paper, the optical properties of ultra-thin chrome, nickel and titanium films are studied by using terahertz differential time-domain spectroscopy to obtain the refractive index and extinction coefficient in the terahertz band. According to the Fresnel formula, the incident medium is high resistance GaAs , The reflectance spectrum of the GaAs / Metal interface and the average reflectivities of the three metals over the wavelength band of 0.3-1.5 THz exceeded 80%. Studying the reflection characteristics of ultra-thin metal film in the terahertz wave band provides a basis for designing terahertz radiation sources, detectors and terahertz optical elements with excellent performance.