title: Toroidal Dipolar Excitation in Metamaterials Consisting of Metal nanodisks and a Dielectrc Spacer on Metal Substrate.
abstract: We have investigated numerically toroidal dipolar excitation at optical frequency in metamaterials whose unit cell consists of three identical Ag nanodisks and a SiO2spacer on Ag substrate. The near-field plasmon hybridization between individual Ag nanodisks and substrate forms three magnetic dipolar resonances, at normal incidence of plane electromagnetic waves. The strong coupling among three magnetic dipolar resonances leads to the toroidal dipolar excitation, when space-inversion symmetry is broke along the polarization direction of incident light. The influences of some geometrical parameters on the resonance frequency and the excitation strength of toroidal dipolar mode are studied in detail. The radiated power from toroidal dipole is also compared with that from conventional electric and magnetic multipoles.
authors.affiliation: Center for Optics & Optoelectronics Research and Department of Applied Physics, Zhejiang University of Technology, Hangzhou, 310023, China.
authors.forename: Chaojun
authors.initials: C
authors.lastname: Tang
authors.affiliation: Center for Optics & Optoelectronics Research and Department of Applied Physics, Zhejiang University of Technology, Hangzhou, 310023, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yan
authors.affiliation: Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa, 50011, USA.
authors.forename: Qiugu
authors.identifier: http://orcid.org/0000-0003-2662-7736
authors.initials: Q
authors.lastname: Wang
authors.affiliation: College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210023, China. jchen@njupt.edu.cn.|National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, China. jchen@njupt.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, China.
authors.forename: Zhendong
authors.initials: Z
authors.lastname: Yan
authors.affiliation: Center for Optics & Optoelectronics Research and Department of Applied Physics, Zhejiang University of Technology, Hangzhou, 310023, China. liufanxin@zjut.edu.cn.|National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, China. liufanxin@zjut.edu.cn.
authors.forename: Fanxin
authors.initials: F
authors.lastname: Liu
authors.affiliation: Center for Optics & Optoelectronics Research and Department of Applied Physics, Zhejiang University of Technology, Hangzhou, 310023, China.
authors.forename: Naibo
authors.initials: N
authors.lastname: Chen
authors.affiliation: Center for Optics & Optoelectronics Research and Department of Applied Physics, Zhejiang University of Technology, Hangzhou, 310023, China.
authors.forename: Chenghua
authors.initials: C
authors.lastname: Sui