基于石墨烯-金属复合超材料结构的电磁诱导透明非线性调制  

Nonlinear Modulation of Electromagnetically Induced Transparency Based on Graphene-Metal Hybrid Metamaterial Structure

作　　者：刘姗姗 李泉[1] 杨子榆 路光达[2] 王爽[1] Liu Shanshan;Li Quan;Yang Ziyu;Lu Guangda;Wang Shuang(School of Electronic,Engineering Tianjin University of Technology and Education,Tianjin 300222,China;Tianjin Key Laboratory of Information Sensing and Intelligent Control,Tianjin University of Technology and Education,Tianjin 300222,China)

机构地区：[1]天津职业技术师范大学电子工程学院,天津300222 [2]天津职业技术师范大学天津市信息传感与智能控制重点实验室,天津300222

出　　处：《中国激光》2021年第19期297-305,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(61705167);天津市科技支撑计划重点项目(20YFZCSY00600);天津市高校中青年骨干创新人才培养计划(2020-04);天津市教委科研计划项目(2020KJ125)。

摘　　要：利用超材料模拟原子系统中的电磁诱导透明现象受到了人们的持续关注,而在超材料中实现主动式电磁诱导透明是其中一个重要的研究方向,在许多领域有着潜在的应用价值。在太赫兹波段上提出了一种新型的主动式电磁诱导透明超材料,其由石墨烯和金属微结构复合而成,其原理是利用金属微结构的场增强特性,结合石墨烯在强场太赫兹下电导率的非线性变化行为,实现对电磁诱导透明效应的非线性调制。为了提升该非线性调制深度,在金属微结构中引入了小开口间隙的谐振单元,以实现更强的近场增强,从而提升石墨烯非线性电导率的变化范围。在0.5μm开口间隙下,模拟获得了高达360.7的场增强因子和49.3%的非线性调制深度。设计思路为实现紧凑的非线性慢光器件提供了参考。Objective Recently,mimicking the quantum electromagnetically induced transparency(EIT)effect using metamaterials in a classical way has attracted continuous attention.Achieving an active EIT effect is one of the important research directions owing to its great potential in many practical applications,such as active light switching and high-speed slow light modulation.So far,a variety of new working schemes have been proposed by integrating functional materials into the metamaterial structures,such as nonlinear media and photoactive and electroactive semiconductors.Graphene,composed of single-layer carbon atoms,exhibits excellent electrical and optical properties and the dynamic tuning of its optical conductivity is achieved by tuning its Fermi level(EF)and carrier scattering time(τ).Based on this,graphene-based active metamaterials have successfully exhibited their potentials in light modulation in which high modulation speed is shown owing to the picosecond-level relaxation time of graphene.However,the previous studies mostly rely on tuning EFto achieve the active control and the studies by tuningτare relatively scarce.In this work,we theoretically proposed an active EIT device in the terahertz regime using graphene-metal hybrid metamaterials,in which we tuneτusing the nonlinear effect of graphene under strong-field terahertz incidence.Owing to the ultrafast relaxation time of the carriers in graphene,such a nonlinear modulation route paves the way towards ultra-fast active devices.Methods The proposed active EIT metamaterial is composed of graphene-metal hybrid structures on the silicon substrate.The metal structure part is composed of meanderline resonator(MLR)and split ring resonators(SRRs),as shown in Fig.1.The two SRRs are placed vertically and symmetrically inside the MLR.The geometric parameters of the metal structure are:L_(1)=85μm,L_(2)=75μm,d=12.5μm,l_(1)=29μm,l_(2)=25μm,w=6μm,s=7μm,g=0.5μm,and D=53.5μm,respectively.The period is P=100μm,and the thicknesses of the metal and silicon substra

关 键 词：材料 超材料 太赫兹 石墨烯 电磁诱导透明 非线性调制 

分 类 号：O436[机械工程—光学工程]