Research On Design And Experiment Of Metasurface Terahertz Devices

In recent years,terahertz science and technology has attracted more and more attention due to its wide applications in wireless communications,defense radar,security imaging,and biomedical,etc.As a result,terahertz science has entered a stage of rapid development.Metasurface,as an artificial structure with high design flexibility,which can produce a unique electromagnetic response with terahertz waves.Therefore,metasurface has a great role in promoting the development of terahertz science and technology.At present,various terahertz functional devices such as absorbers,filters,and modulators are emerging in an endless stream,and excellent performance has been achieved.However,in the research of metasurface terahertz functional devices,there are deficiencies such as single fixed function,complex preparation process,and expensive equipment,which hinder the development of terahertz devices.Therefore,based on the electromagnetic characteristics and theoretical analysis of the metasurface,we focus on the research of terahertz devices with different functions.In this paper,four kinds of metasurface terahertz devices with different functions including modulator,polarization converter,resonator,and absorber are designed.Finally,the performance of these devices is analyzed and verified by simulation and experimental measurement.Firstly,based on the regulation mechanism of active materials on the electromagnetic properties of metasurface,a general method to realize terahertz functional modulation devices is proposed.In this paper,semiconductor InSb is used as the active tunable material to combine with all-dielectric metasurface terahertz devices.As a result,the effect of temperature on the permittivity of InSb is used to realize the regulation of terahertz device functional characteristics.And the all-dielectric absorber and all-dielectric grating filter are taken as examples to verify the feasibility of this method.Finally,combined with CST simulation software,this paper analyzes the resonant characteristics of devices at different temperatures,to further expand the application range of metasurface terahertz functional devices.Then,after studying the tunable mechanism of InSb for the metasurface terahertz devices,a design method of tunable terahertz polarization converter is proposed.With the influence of InSb,the converter can not only realize the perfect conversion from terahertz linear polarization wave to circular polarization wave,but also realize the control of the working frequency and polarization state of the output terahertz wave.The research of polarization converter has a certain reference significance for the development of wireless communication and sensor imaging.Then,after the simulation and theoretical analysis,we begin to analyze the performance of the metasurface terahertz device through experimental measurement.In this paper,a high-throughput,low-cost terahertz resonator fabrication technology is proposed.By mixing ceramic powder with polymer particles,and using the grid to select the target size particles,the large-scale fabrication of flexible terahertz resonators can be realized.Then,through the terahertz time-domain spectrometer,we test and verify the resonant characteristics of terahertz devices.Combined with the Mie resonance theory for supplementary analysis,we in-depth analyze the resonant principle and electromagnetic response characteristics of terahertz devices.This technology has a certain guiding significance for the realization of low-cost and high-throughput fabrication of metasurface terahertz devices.Finally,we further improve the preparation process of micro particles,and based on the micro template-assisted self-assembly method,we propose a high-precision and high-efficiency terahertz absorber fabrication technology,which realizes the fabrication of three band absorber and ultra-wideband absorber.In addition,the performance of terahertz reflectance time-domain spectroscopy system is used to measure the performance of these absorbers.Finally,the working principle and absorption characteristics of terahertz absorber are deeply studied by combining with multiple interference/reflection theory.This method provides a promising platform for the development of efficient and multifunctional terahertz devices.