Subwavelength localization and toroidal dipole moment of spoof surface plasmon polaritons

Kim, Seong-Han, Oh, Sang Soon ORCID: https://orcid.org/0000-0003-3093-7016, Kim, Kap-Joong, Kim, Jae-Eun, Park, Hae Yong, Hess, Ortwin and Kee, Chul-Sik 2015. Subwavelength localization and toroidal dipole moment of spoof surface plasmon polaritons. Physical Review B 91 (3) , 035116. 10.1103/PhysRevB.91.035116

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Abstract

We experimentally and theoretically demonstrate subwavelength scale localization of spoof surface plasmon polaritons at a point defect in a two-dimensional groove metal array. An analytical expression for dispersion relation of spoof surface plasmon polaritons substantiates the existence of a band gap where a defect mode can be introduced. A waveguide coupling method allows us to excite localized spoof surface plasmon polariton modes and measure their resonance frequencies. Numerical calculations confirm that localized modes can have a very small modal volume and a high Q factor both of which are essential in enhancing light-matter interactions. Interestingly, we find that the localized spoof surface plasmon polariton has a significant toroidal dipole moment, which is responsible for the high Q factor, as well as an electric quadrupole moment. In addition, the dispersion properties of spoof surface plasmon polaritons are analyzed using a modal expansion method and numerical calculations.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	1098-0121
Date of First Compliant Deposit:	10 January 2018
Date of Acceptance:	1 January 2015
Last Modified:	06 May 2023 08:26
URI:	https://orca.cardiff.ac.uk/id/eprint/108057

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