Polarized evanescent waves reveal trochoidal dichroism

Lauren A. McCarthy, Kyle W. Smith, Xiang Lan, Seyyed Ali Hosseini Jebeli, Luca Bursi, Alessandro Alabastri, Wei Shun Chang, Peter Nordlander, Stephan Link

Research output: Contribution to journalArticlepeer-review

Abstract

Matter’s sensitivity to light polarization is characterized by linear and circular polarization effects, corresponding to the system’s anisotropy and handedness, respectively. Recent investigations into the near-field properties of evanescent waves have revealed polarization states with out-of-phase transverse and longitudinal oscillations, resulting in trochoidal, or cartwheeling, field motion. Here, we demonstrate matter’s inherent sensitivity to the direction of the trochoidal field and name this property trochoidal dichroism. We observe trochoidal dichroism in the differential excitation of bonding and antibonding plasmon modes for a system composed of two coupled dipole scatterers. Trochoidal dichroism constitutes the observation of a geometric basis for polarization sensitivity that fundamentally differs from linear and circular dichroism. It could also be used to characterize molecular systems, such as certain light-harvesting antennas, with cartwheeling charge motion upon excitation.

Original languageEnglish (US)
Pages (from-to)16143-16148
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number28
DOIs
StatePublished - Jul 14 2020
Externally publishedYes

Keywords

  • Born–Kuhn model for circular dichroism
  • Evanescent field polarization
  • Plasmonic nanorod dimers
  • Single-particle spectroscopy

ASJC Scopus subject areas

  • General

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