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基于VO_(2)的太赫兹各向异性编码超表面

VO_(2)based terahertz anisotropic coding metasurface
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摘要 设计了一种3层结构的太赫兹编码超表面,其顶部是嵌入VO_(2)的金属十字架结构,中间是聚酰亚胺,底部为纯金属.利用该编码超表面的各向异性特点,可以实现对正交极化波(x极化波和y极化波)的独立调控;通过在编码超表面中引入VO_(2)材料,改变其相变状态,可进一步增加调控的灵活性.对设计的超表面进行建模仿真和分析,结果表明:对于垂直入射的1 THz正交极化波,VO_(2)处于绝缘态时,设计的超表面可视为2 bit的各向异性编码超表面,产生模式为1和2的涡旋波;VO_(2)处于金属态时,设计的超表面可视为1 bit的各向异性编码超表面,产生对称的2束反射波和4束反射波.所提出的各向异性和相变材料结合的方法,实现了同一超表面上产生多种不同形式太赫兹波束的功能,一定程度上解决了超表面调控太赫兹波形式单一的问题,为实现能够灵活应用于多种场景的多功能编码超表面提供了参考. Terahertz(THz)wave has the advantages of high resolution,large information capacity,easy beam focusing,etc,and can be used in the fields of communication,radar,detection and others.Firstly,as a two-dimensional artificial electromagnetic metamaterial,the coding metasurface is proposed in the microwave band.It uses the digital coding of the electromagnetic wave phase to adjust electromagnetic waves.Subsequently,as an important way to regulate THz,the metasurface extends to terahertz frequency band and becomes a research hotspot.In this paper,we design a coding metasurface based on vanadium dioxide(VO_(2))with anisotropic characteristics.It is composed of three layers,with a metal cross structure embedded in VO_(2)at the top,polyimide in the middle,and pure metal at the bottom.The design of the cross shaped structure makes the coding metasurface unit anisotropic,which can provide complete and independent control of the orthogonally linearly polarized incident waves.The pure metal structure at the bottom can provide higher reflection amplitude for the incident wave.And VO_(2)is introduced into the coding metasurface.As a phase change material,VO_(2)can switch its properties between the insulating state and the metallic state,which further increases the flexibility of coding metasurface to regulate THz wave.Eight different coding metasurface units are designed in this work.They can be arranged according to a reasonable coding sequence to form a coding metasurface,which consisits of 20×20 metasurface units with an overall size of 2.4 mm×2.4 mm.Its coding sequence will be changed with the phase of VO_(2),thus forming a corresponding 1 bit or 2 bit coding metasurface,and the generated beam form changes accordingly.The finite-difference time domain method is used for modeling and implementing simulation,and the results are as follows.The 1-THz orthogonal linearly polarized wave is vertically incident on the coding metasurface.When VO_(2)is in the insulating state,the designed metasurface can be regarded as an anisotropic 2 bit coding metasurface to generate dual-polarization orbital angular momentum(OAM)vortex beams.The x-polarized vortex wave has an OAM mode number of 2,and the y-polarized vortex wave possesses an OAM mode number of 1.When VO_(2)is in the metallic state,the designed metasurface can be regarded as an anisotropic 1 bit coding metasurface to generate dual-polarization symmetrical beams.Four reflected waves are generated by incident x-polarized waves,and two reflected waves are created by incident y-polarized waves.The proposed method of combining anisotropy material and phase change material realizes the function of generating multiple THz beams in different forms on the same metasurface.The present results provide a reference for the implementation of multi-functional coding metasurface that can be flexibly applied to multiple scenes.
作者 汪静丽 杨志雄 董先超 尹亮 万洪丹 陈鹤鸣 钟凯 Wang Jing-Li;Yang Zhi-Xiong;Dong Xian-Chao;Yin Liang;Wan Hong-Dan;Chen He-Ming;Zhong Kai(College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,China;Bell Honors School,Nanjing University of Posts and Telecommunications,Nanjing 210023,China;Key Laboratory of the Ministry of Education on Optoelectronic Information Technology,School of Precision Instrument and Opto-Electronics Engineering,Tianjin University,Tianjin 300072,China)
出处 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第12期130-138,共9页 Acta Physica Sinica
基金 国家自然科学基金(批准号:12174199,61571237) 江苏省自然科学基金(批准号:BK20221330,BK20151509) 多功能太赫兹天线的研究横向课题(批准号:2021外323)资助的课题。
关键词 太赫兹 编码超表面 VO_(2) 各向异性 terahertz coding metasurface VO_(2) anisotropy
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