金属镜面上纳米光学天线阵列自发辐射增强与定向辐射  

Spontaneous emission enhancement and directional emission by an optical nanonatenna array on a metallic mirror

作　　者：苏宇航 张炼 陶灿 王宁 马平准[1,2] 钟莹 刘海涛[1,2] Su Yu-Hang;Zhang Lian;Tao Can;Wang Ning;Ma Ping-Zhun;Zhong Ying;Liu Hai-Tao(Institute of Modern Optics,College of Electronic Information and Optical Engineering,Nankai University,Tianjin 300350,China;Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology,Nankai University,Tianjin 300350,China;State Key Laboratory of Precision Measurement Technology and Instruments,School of Precision Instrument and Opto-Electronics Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]南开大学电子信息与光学工程学院,现代光学研究所,天津300350 [2]南开大学,天津市微尺度光学信息技术科学重点实验室,天津300350 [3]天津大学精密仪器与光电子工程学院,精密测试技术及仪器国家重点实验室,天津300072

出　　处：《物理学报》2023年第7期376-389,共14页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62075104,61775105)资助的课题.

摘　　要：本文提出一种金属镜面上纳米光学天线阵列结构,天线采用金纳米立方体,单个点辐射源位于天线和金镜面之间的纳米间隙内.天线和金镜面之间的纳米间隙支持间隙表面等离激元,能够增强自发辐射速率;同时,周期排布的纳米天线支持表面晶格共振(surface lattice resonance,SLR),通过适当设计阵列周期,可实现沿垂直于基底方向的远场定向辐射.本文结合阵列扫描法(array scanning method,ASM)和全波严格数值方法,计算了辐射源的自发辐射速率.对于远场辐射强度角分布的计算,本文给出了互易定理方法的严格表述和证明过程,该证明过程不同于已有文献中的证明过程,对于无限大周期结构具有更严格的适用性,或者具有更低的计算量.本文提出的天线结构和设计方法可用于指导设计高速、高亮度、定向辐射光源.Optical nanoantennas support surface plasmon polariton(SPP)with a confinement of light breaking through the diffraction limit,and thereby achieving an enhancement and regulation of electromagnetic field on a deep-subwavelength scale.In this paper,a periodic array of optical nanoantennas on a metallic mirror is proposed,where the antennas are gold nanocubes forming a two-dimensional periodic array,and a single point emission source is located in the nanogap between the antenna of gold nanocube and the gold mirror.The nanogap between the antenna and mirror can support gap surface plasmon,which results in an enhanced spontaneous emission rate.Meanwhile,the periodic array of nanoantennas can support the surface lattice resonance(SLR),which can achieve directional far-field radiation perpendicular to the substrate or in a specified direction by properly designing the array period.To design the antenna that can simultaneously achieve an enhancement of spontaneous emission rate and a directional radiation of far field,the calculation of the radiation field of a single point source in a periodic structure is transformed into the calculation of the radiation fields of a set of pseudoperiodic point-source arrays by combining the array scanning method(ASM)and full-wave rigorous numerical method,thus giving the spontaneous emission rate of the emitter and the near-field distribution of the antenna.Concerning the calculation of the angular distribution of far-field radiation intensity,we start from the Maxwell’s equations and provide a rigorous formulation and proof of the reciprocity-theorem method.This proof is different from those reported in existing literature and has a more rigorous applicability for infinite-extent periodic structures or has a lower amount of computational work.Based on the reciprocity-theorem method,the antenna parameters are designed so that the enhancement factor of far-field radiation intensity reaches a maximum value of 2756 in the direction perpendicular to the substrate,and simultaneously,the

关 键 词：金属镜面上纳米光学天线阵列 自发辐射增强 远场定向辐射 互易定理 

分 类 号：TN820[电子电信—信息与通信工程]