Beaming of Helical Light from Plasmonic Vortices via Adiabatically Tapered Nanotip

Denis Garoli, Pierfrancesco Zilio, Yuri Gorodetski, Francesco Tantussi, Francesco De Angelis

Research output: Contribution to journalArticlepeer-review

Abstract

We demonstrate the generation of far-field propagating optical beams with a desired orbital angular momentum by using a smooth optical-mode transformation between a plasmonic vortex and free-space Laguerre-Gaussian modes. This is obtained by means of an adiabatically tapered gold tip surrounded by a spiral slit. The proposed physical model, backed up by the numerical study, brings about an optimized structure that is fabricated by using a highly reproducible secondary electron lithography technique. Optical measurements of the structure excellently agree with the theoretically predicted far-field distributions. This architecture provides a unique platform for a localized excitation of plasmonic vortices followed by its beaming.

Original languageEnglish
Pages (from-to)6636-6643
Number of pages8
JournalNano Letters
Volume16
Issue number10
DOIs
StatePublished - 12 Oct 2016

Keywords

  • Laguerre Gaussian beam
  • Plasmonic vortex
  • orbital angular momentum
  • singular optics
  • spin-orbit coupling

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Condensed Matter Physics
  • Mechanical Engineering
  • Bioengineering
  • General Materials Science

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