摘要
设计了一种四宽带且吸收率动态可调的太赫兹吸收器,该吸收器结构简单,由顶层二氧化钒、中间层二氧化硅和底层金属组成。仿真结果表明,在0~10 THz范围内,吸收率超过90%的吸收带共有4个,带宽分别为0.87、0.58、0.61、0.45 THz。随二氧化钒电导率的变化,吸收率可在7.7%~99.9%范围内动态调节。引入阻抗匹配理论和法布里-珀罗共振理论解释了吸收器的物理机理,并通过电场分布分析了多个完美吸收峰的物理来源。此外,该吸收器还具有偏振不敏感和广角吸收的特点,可在微辐射计、生物传感器和隐身技术等领域应用。
Objective Since the first metamaterial perfect absorber was proposed by Landy et al.,it has been widely developed due to its potential applications in the fields of microwave radiation measurement,biosensors,thermal emitters,and imaging.Many existing absorbers face the issue of narrow bandwidths,which fail to satisfy the demands of some optoelectronic devices.To solve this problem,it is common to construct different patterns in the same layer or stack multilayer structures with different geometrical dimensions.However,these structures are often complex,and the absorption rate cannot be actively adjusted.Therefore,phase change materials have been introduced to regulate the absorption rate of absorbents,and vanadium dioxide is one of them.There are many absorbers designed with VO_(2),but the absorption bandwidth and band number need to be further increased.Therefore,combining the characteristics of multi-band,wideband,and tunable absorption remains a meaningful endeavor.Methods To effectively study the performance of the absorber,the proposed structure is analyzed by using the microwave simulation software CST Microwave Studio 2020.The metamaterial absorber in this study consists of three layers:the top layer VO_(2),the middle layer SiO_(2),and the bottom layer Au.When the conductivity is adjusted from 200 S/m to 2×10^(5) S/m,VO_(2) will change from an insulator to metal,which can be simulated by input conductivity parameters through the Drude model in CST software.The absorber s absorption can be obtained through one minus the reflection and transmission.Since the penetration depth of the incident wave is smaller than the Au thickness,thus the transmittance is zero.Perfect absorption can be achieved when the reflection is also zero.Material selection and structural design are used to achieve impedance matching,ensuring zero reflection and ultimately realizing perfect absorption of multiple broadbands.Results and Discussions The simulation results show that there are four absorption bands with more than 90%of absorptivity in the range of 0?10 THz,covering bandwidths of 0.87,0.58,0.61,and 0.45 THz,respectively.With variations in the conductivity of VO_(2),the absorptivity dynamically adjusts between 7.7% and 99.9%(Fig.2).The analysis finds that with the change of dielectric constant of vanadium dioxide,the resonant frequency remains almost constant,while the absorption rate changes significantly.The Fabry-Perot resonance theory and impedance matching theory are introduced to explain the effects of the dielectric layer and the VO_(2) layer on the absorption(Figs.3-5).The physical sources of multiple perfect absorption peaks are analyzed through the electric field distribution(Fig.6).Additionally,changes in absorptivity with different incident angles and polarization angles are analyzed(Fig.7),which shows that the absorber has the characteristics of polarization insensitivity and wide-angle absorption.Conclusions We describe a terahertz absorber with four absorption bands,dynamically adjustable absorptivity,and a simple structure.Simulation results indicate that within the range of 0-10 THz,there are four absorption bands with more than 90%absorptivity,and their respective bandwidths are 0.87,0.58,0.61,and 0.45 THz.The absorptivity can be dynamically adjusted between 7.7%and 99.9%by varying the conductivity of vanadium dioxide.The physical mechanism of the absorber is explained using impedance matching theory and Fabry-Perot resonance theory.Through the analysis of the electric field distribution,it is found that the first broadband absorption is mainly caused by the local absorption of VO_(2),while the second,third,and fourth broadband absorptions result from the resonance absorption of multiple electric dipoles on the surface of VO_(2),coupled with the coupling effects between the dielectric layer and VO_(2) and the metal layer.Additionally,it has the features of wide-angle absorption and polarization insensitivity.This absorber has potential applications in micro-radiometers,biosensors,stealth technology,and other fields.
作者
张婷
郭泰铭
闫俊伢
裴娅男
Zhang Ting;Guo Taiming;Yan Junya;Pei Yanan(College of Information Engineering,Shanxi Vocational University of Engineering Science and Technology,Jinzhong 030619,Shanxi,China;College of Instrumentation and Electronics,North University of China,Taiyuan 030051,Shanxi,China;The University of Queensland,Brisbane 4072,Queensland,Australia)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2024年第5期222-229,共8页
Acta Optica Sinica
基金
国家自然科学基金(61501213)
山西省基础研究计划(自由探索类)青年科学研究项目(202203021222127)
山西工程科技职业大学校科研基金(KJ202221)。
作者简介
通信作者:张婷,zhangting_cai@163.com。
