Morphology dependence of nanoparticle-on-mirror geometries: a quasinormal mode analysis

Kalun Bedingfield, Eoin Elliott, Nuttawut Kongsuwan, Jeremy J. Baumberg, Angela Demetriadou

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Abstract

Plasmonic nanoantennas are able to produce extreme enhancements by concentrating electromagnetic fields into sub-wavelength volumes. Recently, one of the most commonly used nanoantennas is the nanoparticle-on-mirror geometry, which allowed for the room temperature strong coupling of a single molecule. Very few studies offer analysis of near-field mode decompositions, and they mainly focus on spherical and/or cylindrically-faceted nanoparticle-on-mirror geometries. Perfectly spherical nanoparticles are not easy to fabricate, with recent publications revealing that a rhombicuboctahedron is a commonly occurring nanoparticle shape – due to the crystalline nature of metallic nanoparticles. In this paper, we perform a quasi-normal mode analysis for the rhombicuboctahedron-on-mirror nanoantenna and map the field distributions of each mode. We examine how the geometry of the cavity defines the near-field distribution and energies of the modes, and we show that in some cases the mode degeneracies break. This has a significant impact on the radiative emission and far-field profile of each mode, which are measured experimentally. Understanding how realistic nanoantenna geometries behave in the near-field and far-field helps us design antennas with specific properties for controlling and sensing quantum emitters in plasmonic systems.
Original languageEnglish
Article number3
Number of pages5
JournalEPJ Applied Metamaterials
Volume9
Issue number3
DOIs
Publication statusPublished - 10 Feb 2022

Keywords

  • polygon
  • NPoM
  • nanocavity
  • quasinormal mode
  • plasmonic nanoantenna

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