基于石墨烯和二氧化钒的太赫兹宽带可调谐超材料吸收器  

Terahertz Broadband Tunable Metamaterial Absorber Based on Graphene and Vanadium Dioxide

作　　者：刘苏雅拉图 王宗利 庞慧中 田虎强 王鑫 王俊林 LIU Su-ya-la-tu;WANG Zong-li;PANG Hui-zhong;TIAN Hu-qiang;WANG Xin;WANG Jun-lin(College of Electronic and Information Engineering,Inner Mongolia University,Huhhot 010021,China)

机构地区：[1]内蒙古大学电子信息工程学院,内蒙古呼和浩特010021

出　　处：《光谱学与光谱分析》2022年第4期1257-1263,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(51965047);内蒙古自治区科技攻关项目(2020GG0185)资助。

摘　　要：太赫兹超材料吸收器作为一种重要的太赫兹功能器件,被广泛应用于生物医学传感、电磁隐身、军用雷达等多个领域。但这种传统的超材料吸收器结构具有可调谐性差、功能单一、性能指标不足等缺点,已经无法满足复杂多变的电磁环境的要求,因此可调谐超材料吸收器逐渐成为了太赫兹功能器件领域的研究热点。为实现超材料吸收器吸收特性的调谐,通常从调节谐振单元或基底材料的电磁特性或调节超材料结构单元的几何尺寸两个方面出发。设计了一种基于石墨烯和二氧化钒的太赫兹宽带可调谐超材料吸收器。该吸收器由工字型二氧化钒谐振层、连续石墨烯层和被Topas介质隔开的金属反射层组成。数值模拟结果表明,当二氧化钒材料处于全金属状态(电导率为200 000 S·m^(-1))且石墨烯的费米能级设为0.1 eV时,吸收率超过90%的吸收带宽达到了2.8 THz。通过调节石墨烯的费米能级,使其在0.1~0.3 eV之间变化时,该吸收器的工作频率发生了明显的蓝移。由于二氧化钒材料从绝缘状态到金属状态的相变特性,通过控制电导率使其在100~200 000 S·m^(-1)之间变化时,所提出的宽频结构在反射器和吸收器两种工作状态之间自由切换。此外,还分别监测了该超材料吸收器在1.87,3.04和4.16 THz三个完美吸收峰处的表面电流分布,讨论了其工作机理。所设计的结构通过石墨烯和二氧化钒两个独立可调“开关”实现了对吸收器工作频率和吸收振幅的双重控制,为设计多功能太赫兹器件提供了新的发展思路。Terahertz metamaterial absorbers,as a kind of important terahertz functional devices,are widely used in biomedical sensing,electromagnetic stealth,military radar and other fields.However,this traditional metamaterial absorber structure has disadvantages such as poor tenability,single function and insufficient performance indexes,which can no longer meet the complex and changeable electromagnetic environment requirements.Therefore,the tunable metamaterial absorber has gradually become a research hotspot in the field of terahertz functional devices.In order to achieve the tuning of the absorption characteristics of the metamaterial absorber,the electromagnetic characteristics of the resonance unit or the substrate material or the geometric size of the metamaterial structural unit are usually adjusted.A terahertz broadband tunable metamaterial absorber based on graphene and vanadium dioxide is proposed in this paper.The absorber consists of a vanadium dioxide resonant layer,a continuous graphene layer and a metal reflector separated by a Topa’s medium.The numerical simulation results show that when the material is in the all-metal state(electrical conductivity of 200 000 S·m^(-1)),and the Fermi energy of graphene is set as 0.1 eV,the absorption bandwidth of more than 90% reaches 2.8 THz.When the Fermi energy of graphene is adjusted to change between 0.1 and 0.3 eV,the operating frequency of the absorber shows an obvious blue shift.The proposed broadband structure can switch freely between the reflector and the absorber when the conductivity of vanadium dioxide varies between 100~200 000 S·m^(-1) due to the phase transformation characteristics of vanadium dioxide material from the insulating state to the metallic state.In addition,the surface current distribution of the metamaterial absorber at the three perfect absorption peaks of 1.87,3.04 and 4.16 THz was monitored respectively,and its working mechanism was discussed.The structure designed in this paper realizes the dual control of the absorber’s operating f

关 键 词：太赫兹 可调谐 宽带吸收器 石墨烯 二氧化钒 

分 类 号：TN214[电子电信—物理电子学]