Research On Absorption Characteristics Of Terahertz Metamaterials Based On Subwavelength Metal Structure

Metamaterials are artificially manufactured periodic structures in the sub-wavelength band.In the terahertz band,they have many electromagnetic properties that are not available in natural materials in nature.Multi-frequency terahertz metamaterial absorbers can have the advantages of perfect absorption,ultra-thin thickness,and convenient and flexible design of absorbing frequencies through reasonable design of the overall structure and geometric dimensions,which play an important role in the development of the terahertz field.In this paper,CST simulation software is used to simulate the terahertz metamaterial absorber,and a multi-frequency terahertz absorber with modulation in the 1.0THz to 3.5THz band is designed.The absorber is composed of three layers,and the upper layer is a metal micro Structure,the middle layer is a layer of terahertz medium,the selected material is polyimide,the bottom layer is a thin metal plate structure,and the metal microstructure on the surface layer is an enclosed structure composed of multiple squares.The simulation results show that the structure has three absorption peaks,located at 1.5 THz,2.2 THz,and 2.9 THz.The peak absorption rates are 95.1%,78.2%,and 91.0%,respectively,which have a very high absorption rate for terahertz light waves.Then the terahertz metamaterial absorber was prepared experimentally and tested.In the experiment,the laser direct writing system was used to prepare,and the THz-TDS system was used for testing,and compared with the CST simulation results,the absorption rate reached a higher level.Analyzing the true influence of each parameter on the absorption rate of the structure under the experimental conditions,a novel method for the frequency band of the multi-frequency terahertz metamaterial absorber is proposed.