Interfering plasmons in coupled nanoresonators to boost light localisation and SERS

Angelos Xomalis, Xuezhi Zheng, Angela Demetriadou, Alejandro Martinez, Rohit Chikkaraddy, Jeremy J. Baumberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Plasmonic self-Assembled nanocavities are ideal platforms for extreme light localization as they deliver mode volumes of <50 nm3. Here we show that high-order plasmonic modes within additional micrometer-scale resonators surrounding each nanocavity can boost light localization 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 subnanometer gaps with micrometer-scale resonators places a high computational demand on simulations, so a generalized boundary element method (BEM) solver is developed which requires 100-fold less computational resources to characterize these systems. Our results on extreme near-field enhancement open new potential for single-molecule photonic circuits, mid-infrared detectors, and remote spectroscopy.

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

Bibliographical note

Funding Information:
We acknowledge support from the European Research Council (ERC) under the Horizon 2020 Research and Innovation Programme THOR (829067), POSEIDON (861950) and PICOFORCE (883703). We acknowledge funding from the EPSRC (Cambridge NanoDTC EP/L015978/1, EP/L027151/1, EP/S022953/1, EP/P029426/1, and EP/R020965/1). R.C. acknowledges support from Trinity College, University of Cambridge. A.D. acknowledges support from the Royal Society University Research Fellowship URF/R1/180097 and the Royal Society Research Fellows Enhancement Award RGF/EA/181038.

Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.


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

ASJC Scopus subject areas

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


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