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Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods

Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods
Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods
We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration-a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and appears as a Fano resonance dip in the forward scattered light. We provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.
1550-235X
1-12
Watson, Derek W.
4cb78431-9921-4c6e-9d68-0e8eaa3628e5
Jenkins, Stewart D.
65d861fb-b85a-4927-805a-7c906fca26c6
Ruostekoski, Janne
2beb155e-64b0-4ee9-9cfe-079947a9c9f4
Fedotov, Vassili A.
3725f5cc-2d0b-4e61-95c5-26d187c84f25
Zheludev, Nikolay I.
32fb6af7-97e4-4d11-bca6-805745e40cc6
Watson, Derek W.
4cb78431-9921-4c6e-9d68-0e8eaa3628e5
Jenkins, Stewart D.
65d861fb-b85a-4927-805a-7c906fca26c6
Ruostekoski, Janne
2beb155e-64b0-4ee9-9cfe-079947a9c9f4
Fedotov, Vassili A.
3725f5cc-2d0b-4e61-95c5-26d187c84f25
Zheludev, Nikolay I.
32fb6af7-97e4-4d11-bca6-805745e40cc6

Watson, Derek W., Jenkins, Stewart D., Ruostekoski, Janne, Fedotov, Vassili A. and Zheludev, Nikolay I. (2016) Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods. Physical Review B, 93 (125420), 1-12. (doi:10.1103/PhysRevB.93.125420).

Record type: Article

Abstract

We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration-a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and appears as a Fano resonance dip in the forward scattered light. We provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.

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Accepted/In Press date: 3 February 2016
e-pub ahead of print date: 16 March 2016
Published date: 16 March 2016
Organisations: Optoelectronics Research Centre, Mathematical Sciences, Applied Mathematics

Identifiers

Local EPrints ID: 390261
URI: https://eprints.soton.ac.uk/id/eprint/390261
ISSN: 1550-235X
PURE UUID: 48cae4b3-3278-4517-ad96-99a75b35122e
ORCID for Nikolay I. Zheludev: ORCID iD orcid.org/0000-0002-1013-6636

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Date deposited: 22 Mar 2016 14:01
Last modified: 10 Dec 2019 01:56

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