Functional Analysis And Experimental Observation Of Several Kinds Of Terahertz Devices Based On Metasurfaces

In recent years, terahertz technology has made a huge progress, many THz sources and detectors has been achieved, applications such as THz-TDS-spectrometer, THz imaging technology has also been reported. Recently, metasurfaces become one of the hottest topics. Metasurface which is ultra-thin, small and have many properties that the natural materials do not have, consists of a series of periodically arranged antennas. With the development of the research, many devices based on metasurfaces have been reported, such as metasurface beam splitter, OAM and Bessel beam generator, metalens. Due to the lack of suitable natural materials, terahertz devices, such as terahertz wave plate, beam splitter and other functional devices, remain a challenge for a long time, it also hinders the study of THz wave in other directions. The study on terahertz metasurface devices makes it possible to fill this gap.This paper focus on the study of THz metasurfaces, first itroduces the properties of terahertz wave, the background and the status of research on THz technology and metasurfaces, and the fabrication technology. Then it systematically elaborates the principle of geometrical optics of metasurface devices. In this paper, the metasurface is designed and analysed through Finite Difference Time Domain(FDTD) method. In order to choose the right size of antenna, each single antenna is analysed by simulation. Three kind of THz metasurfaces are designed to achieve different functions such as anomalous reflection of THz wave, THz polarization converters and THz OAM beam generator. Then photolithography and electron beam evaporation technology are used to fabricate the sample. The results in the experiment are in good agreement with the simulation. Terahertz metasurface devices are of great significance for the research of terahertz wave. The research on the fabrication technology also provides much experience of making the sample. The experimental results verify the feasibility of the terahertz metasurface devices. It may have many potential applications in THz technology in the future.