摘要
提出了一种基于二氧化钒-狄拉克半金属混合超材料的单/双波段可切换太赫兹吸波器设计。利用二氧化钒的可逆相变特性来实现单/双波段功能之间的切换,当二氧化钒处于绝缘态时,通过改变狄拉克半金属的费米能级能量,可实现吸收峰值大小和位置的调控。数值仿真表明:当二氧化钒处于绝缘态且狄拉克半金属的费米能级能量设定为160 meV时,吸波器可以在0.97 THz和3.152 THz处出现两个吸收峰,吸收率分别为99.3%和99.7%,均超过了99%,说明在这两个谐振频率点处实现了几乎完美的吸收。而当二氧化钒变为金属态且狄拉克半金属的费米能级能量为160 meV时,吸波器在4.246 THz处出现一个吸收峰,吸收峰值超过98%。实际上,由于狄拉克半金属的存在,吸收率会受到费米能级能量的影响,仿真结果发现:当VO_(2)处于绝缘态时,狄拉克半金属费米能级能量对吸收峰值和谐振频率点有较大的影响;然而,当VO_(2)处于金属态时,狄拉克半金属的费米能级能量几乎不会改变吸收峰值和谐振频率。为了验证吸波器的吸波机理,引入阻抗匹配理论对吸波器进行分析。所提出的可切换超材料吸波器可以广泛地应用于成像等领域。
Objective Terahertz absorbers have become hot due to their widely applications in sensing,detection,and other fields.Metamaterials are a type of artificial composite material which are composed of sub-wavelength micro-units arranged in a specific period.They have many excellent physical properties that natural materials do not have.Although these metamaterial-based absorbers can achieve a perfect absorption by designing different resonator shapes,but it is difficult to adjust the absorption performances once the structure is manufactured,which hinders the potential of a metamaterial absorber in practical applications.Therefore,combining functional materials with metamaterial devices to form absorbers with tunable characteristics is more and more important.Vanadium dioxide(VO_(2))is a kind of reversible phase change material,which can transform from an insulator to a metallic state at about 340 K when the conductivity changes by 4-5 orders of magnitude,so VO_(2)is also widely used in optical devices.Moreover,one can change the relative permittivities of three-dimensional bulk Dirac semi-metals(BDSs),also known as 3D graphene,by adjusting their Fermi level energies.In this paper,a single-/dual-band switchable terahertz absorber based on VO_(2)-BDSs hybrid metamaterials is proposed,which uses the reversible phase transition characteristics of VO_(2)to realize the conversion between single-/dual-band functions.Moreover,the value and position of the absorption peak can be achieved by changing the Fermi level energy of BDSs.Methods The proposed absorber consists of five layers:VO_(2)resonance layer,upper TOPAS dielectric layer 1,middle BDSs resonance layer,lower TOP AS dielectric layer 2,and metal substrate(Fig.1).The VO_(2)resonance layer and the BDSs resonance layer are composed of a rectangular film and a split ring,respectively.In modeling and simulation,we select the frequency domain solver in CST Microwave Studio.For the boundary condition setting,we set the unit cell in both x and y directions,and apply the open
作者
易南宁
宗容
龚江
段韬
钱蓉蓉
Yi Nanning;Zong Rong;Gong Jiang;Duan Tao;Qian Rongrong(School of Information,Yunnan University,Kunming,Yunnan,650500,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第3期180-189,共10页
Chinese Journal of Lasers
基金
国家自然科学基金(61701433)
云南省科技厅面上项目(2018FB099)。
关键词
材料
光学设备
太赫兹
二氧化钒
狄拉克半金属
吸收
material
optical device
terahertz
vanadium dioxide
Dirac semimetal
absorption
