Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film

Abstract We present scanning near-field images of surface plasmon modes around a single elliptical nanohole in 88 nm thick Au film. We find that rotating surface plasmon vortex modes carrying extrinsic orbital angular momentum can be induced under linearly polarized illumination. The vortex modes ar...

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Autores principales:	Claudia Triolo, Salvatore Savasta, Alessio Settineri, Sebastiano Trusso, Rosalba Saija, Nisha Rani Agarwal, Salvatore Patanè
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2019
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/30aae2e26f3242d493de0b9686869d02
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id	oai:doaj.org-article:30aae2e26f3242d493de0b9686869d02
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spelling	oai:doaj.org-article:30aae2e26f3242d493de0b9686869d022021-12-02T15:08:21ZNear-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film10.1038/s41598-019-41781-22045-2322https://doaj.org/article/30aae2e26f3242d493de0b9686869d022019-03-01T00:00:00Zhttps://doi.org/10.1038/s41598-019-41781-2https://doaj.org/toc/2045-2322Abstract We present scanning near-field images of surface plasmon modes around a single elliptical nanohole in 88 nm thick Au film. We find that rotating surface plasmon vortex modes carrying extrinsic orbital angular momentum can be induced under linearly polarized illumination. The vortex modes are obtained only when the incident polarization direction differs from one of the ellipse axes. Such a direct observation of the vortex modes is possible thanks to the ability of the SNOM technique to obtain information on both the amplitude and the phase of the near-field. The presence of the vortex mode is determined by the rotational symmetry breaking of the system. Finite element method calculations show that such a vorticity originates from the presence of nodal points where the phase of the field is undefined, leading to a circulation of the energy flow. The configuration producing vortex modes corresponds to a nonzero total topological charge (+1).Claudia TrioloSalvatore SavastaAlessio SettineriSebastiano TrussoRosalba SaijaNisha Rani AgarwalSalvatore PatanèNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 9, Iss 1, Pp 1-9 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Claudia Triolo Salvatore Savasta Alessio Settineri Sebastiano Trusso Rosalba Saija Nisha Rani Agarwal Salvatore Patanè Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
description	Abstract We present scanning near-field images of surface plasmon modes around a single elliptical nanohole in 88 nm thick Au film. We find that rotating surface plasmon vortex modes carrying extrinsic orbital angular momentum can be induced under linearly polarized illumination. The vortex modes are obtained only when the incident polarization direction differs from one of the ellipse axes. Such a direct observation of the vortex modes is possible thanks to the ability of the SNOM technique to obtain information on both the amplitude and the phase of the near-field. The presence of the vortex mode is determined by the rotational symmetry breaking of the system. Finite element method calculations show that such a vorticity originates from the presence of nodal points where the phase of the field is undefined, leading to a circulation of the energy flow. The configuration producing vortex modes corresponds to a nonzero total topological charge (+1).
format	article
author	Claudia Triolo Salvatore Savasta Alessio Settineri Sebastiano Trusso Rosalba Saija Nisha Rani Agarwal Salvatore Patanè
author_facet	Claudia Triolo Salvatore Savasta Alessio Settineri Sebastiano Trusso Rosalba Saija Nisha Rani Agarwal Salvatore Patanè
author_sort	Claudia Triolo
title	Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
title_short	Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
title_full	Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
title_fullStr	Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
title_full_unstemmed	Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
title_sort	near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film
publisher	Nature Portfolio
publishDate	2019
url	https://doaj.org/article/30aae2e26f3242d493de0b9686869d02
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Near-field imaging of surface-plasmon vortex-modes around a single elliptical nanohole in a gold film

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