对称破缺二聚体混合结构高Q圆二色性  

Circular Dichroism with High Q Factor of Symmetry-Broken Dimeric Hybrid Structure

作　　者：肖功利[1] 周嗣童 杨宏艳[2] 赖子凡 陈佳宇 李海鸥[1] 刘兴鹏 陈赞辉 Xiao Gongli;Zhou Sitong;Yang Hongyan;Lai Zifan;Chen Jiayu;Li Haiou;Liu Xingpeng;Chen Zanhui(Key Laboratory of Microelectronic Devices and Integrated Circuits of Guangxi Colleges,Guilin University of Electronic Technology,Guilin 541004,Guangxi,China;School of Optoelectronic Engineering,Guilin University of Electronic Technology,Guilin 541004,Guangxi,China)

机构地区：[1]桂林电子科技大学广西高校微电子器件与集成电路重点实验室,广西桂林541004 [2]桂林电子科技大学光电工程学院,广西桂林541004

出　　处：《光学学报》2023年第22期258-265,共8页Acta Optica Sinica

基　　金：国家自然科学基金(62165004,61805053);广西自然科学基金(2023GXNSFAA026108);桂林电子科技大学研究生创新项目(2022YCXS047,2021YCXS040)。

摘　　要：圆二色性(CD)通常用来表征手性响应强度,在手性检测领域极具应用前景。本文提出了一种金衬底上对称性破缺的全介质二聚体混合结构,可在721.1 nm波段处产生高达0.42的强CD,并且CD谱具有极窄的线宽,仅为0.16 nm。通过琼斯矩阵对该结构进行了理论分析,采用时域有限差分(FDTD)法进行建模与仿真,研究结果表明,通过改变介质二聚体的尺寸大小或椭圆柱介质的旋转角(θ)和两个介质体的相对位置(G)等参数可以对结构的CD响应进行相应的优化。并且通过电场分析发现,圆偏振光激发了二聚体的表面晶格共振(SLR),导致其CD谱具有高品质因子(Q)特性。基于此结构传感的灵敏度为718.3 nm/RIU(灵敏度单位),Q值可高达4489.4。此外,该手性结构的周期单元可以实现数字成像功能,不同偏振光下具有不同的成像信号。高Q值CD的研究结果为高性能的手性传感及光学成像的研究奠定了一定的理论基础。Objective Circular dichroism(CD)molecular spectroscopy is often employed to determine the glucose content in food and is also an important tool to analyze the secondary structure of proteins and related property information of some viral molecules.However,chromatographic methods commonly adopted for chiral analysis are difficult to meet the rapid development in food,medicine,and biochemistry due to their shortcomings such as cumbersome sample processing,high cost,and much consumed time.Thus,there is an urgent need for more high-performance chiral analytical methods.High-Q and high-speed chiral sensors can solve these problems to a large extent and thus have been extensively applied to the chiral analysis of various fields,with the emergence of various high-Q chiral metamaterial structures.Methods Compared with the traditional chiral structure approaches,we can not only achieve stronger CD and maximize the higher Q factor by avoiding the metal radiation loss but also have a relatively simple structure.By placing a symmetrybroken dielectric dimer structure with a low refractive index on the bottom Au film,the mirror properties of the Au film are utilized to transfer the local field generated by surface lattice resonance(SLR)from the metal surface to the media top,which produces a resonant mode with a narrow linewidth.We simulate the structure using finite difference time domain(FDTD)solutions and theoretically analyze it by the Jones matrix method.The effects of parameters on the CD mode are discussed,such as the dimensional size of the dimer structure,the rotation angle of the ellipsoid column(θ),the relative distance between the square column and the ellipsoid medium(G),and the refractive index of the surrounding environment.Meanwhile,the sensitivity(S)and Q are calculated to quantitatively analyze sensing properties of the refractive index,and a cell with a period of 4×16 is arrayed to validate the structure for specific applications in imaging.Results and Discussions First,we verify the mechanism that the pro

关 键 词：圆二色性 对称破缺 二聚体 表面晶格共振 

分 类 号：TN256[电子电信—物理电子学]