Interfering plasmons in coupled nanoresonators to boost light localisation and SERS

Research output: Contribution to journalArticlepeer-review

Authors

  • Angelos Xomalis
  • Xuezhi Zheng
  • Alejandro Martinez
  • Rohit Chikkaraddy
  • Jeremy J. Baumberg

Colleges, School and Institutes

External organisations

  • Cavendish Laboratory
  • KU Leuven Univ
  • Universidad Politécnica de Valencia
  • Cavendish Laboratory, Department of Physics
  • University of Cambridge
  • Nanophotonics Centre

Abstract

Plasmonic self-assembled nanocavities are ideal platforms for extreme light localisation as they deliver mode volumes <50 nm3 . Here we show that high-order plasmonic modes within additional μm-scale resonators surrounding each nanocavity can boost light localisation to intensity enhancements >105 . Plasmon interference in these hybrid microresonator-nanocavities produces surface-enhanced Raman scattering (SERS) signals many-fold larger than in the bare plasmonic constructs. These now allow remote access to molecules inside the ultrathin gaps, avoiding direct irradiation and thus preventing molecular damage. Combining sub-nm gaps with μm-scale resonators places high computational demand on simulations, so a generalised Boundary Element Method (BEM) solver is developed which requires 100-fold less computational resource to characterise these systems. Our results on extreme near-field enhancement open new potential for single-molecule photonic circuits, mid-infrared detectors, and remote spectroscopy.

Details

Original languageEnglish
Pages (from-to)2512–2518
Number of pages7
JournalNano Letters
Volume21
Issue number6
Early online date11 Mar 2021
Publication statusPublished - 24 Mar 2021

Keywords

  • Nanocavity, field enhancement, near-field, SERS, nano-optics, plasmon interference, remote excitation