紧聚焦角向矢量光激发下硅环-开口金环纳米天线的单向散射  

Unidirectional scattering of Si ring-Au split ring nanoantenna excited by tightly focused azimuthally polarized beam

作　　者：张汉谋 肖发俊[1] 赵建林[1] Zhang Han-Mou;Xiao Fa-Jun;Zhao Jian-Lin(Key Laboratory of Light Field Manipulation and Information Acquisition,Ministry of Industry and Information Technology,and Shaanxi Key Laboratory of Optical Information Technology,School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710029,China)

机构地区：[1]西北工业大学物理科学与技术学院,光场调控与信息感知工业和信息化部重点实验室,陕西省光信息技术重点实验室,西安710029

出　　处：《物理学报》2022年第13期273-280,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2017YFA0303800);国家自然科学基金(批准号:11634010,11874050);陕西省重点研发项目(批准号:2021KW-19);中央高校基本科研业务费(批准号:3102019JC008,D5000210936)资助的课题。

摘　　要：采用时域有限差分法,数值研究了紧聚焦角向矢量光激发下硅环-开口金环纳米天线的远场散射特性.结果表明:紧聚焦的角向矢量光可在硅纳米环和开口金纳米环中分别激发出不同峰宽的磁偶极模式;由于模式间的杂化效应,两种磁偶极模式会耦合形成硅环-开口金环纳米结构的反键和成键模式;在峰谷1064 nm波长处,反键和成键模式间的相消干涉在面内形成了单向远场散射.进一步,详细研究了几何参数对单向散射的影响,并且借助该纳米天线的单向散射特性,实现了偶极光源的定向发射.研究结果提供了一种纳米光子结构远场散射的灵活调控手段,并有望为纳米光源、光学传感器等的设计和研发提供有益的参考.Unidirectional scattering of various plasmonic nanoantennas has been extensively studied,giving birth to applications such as in optical sensors,solar cells,spectroscopy and light-emitting devices.The directional scattering of magnetic nanoantenna is still unexplored,though it is beneficial to artificial magnetism applications including metamaterials,cloaking and nonlinear optical resonance.In this work,we numerically investigate the far-field scattering properties of the Si ring-Au split ring nanoantenna(Si R-Au SRN)excited by a tightly focused azimuthally polarized beam(APB)through using the finite-difference time-domain(FDTD)method.The results show that the magnetic resonant peaks with different widths can be deterministically excited in Si ring and Au split ring by tightly focusing APB.Owing to the plasmon hybridization effect,the two magnetic resonant modes form antibonding mode and bonding mode in the Si R-Au SRN.At a wavelength of λ=1064 nm,the destructive interference between the antibonding mode and bonding mode of nanostructure results in unidirectional far-field scattering in the transverse plane,which is affected dramatically by changes of geometrical parameters.Furthermore,the directional scattering of a dipole source is realized by the designed nanostructure,and its scattering directionality is superior to that excited with APB.Our work provides a flexible way to control the far-field scattering of nano-photon structures.We expect that this study can provide an avenue to the nano-light sources and optical sensors.

关 键 词：单向散射 磁偶极模式 等离激元杂化 开口环谐振器纳米结构 

分 类 号：TN820[电子电信—信息与通信工程]