Interfering plasmons in coupled nanoresonators to boost light localization and SERS

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

Research output: Contribution to journalArticlepeer-review

Abstract

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
JournalNano Letters
Volume21
Issue number6
Early online date11 Mar 2021
DOIs
Publication statusPublished - 24 Mar 2021

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