Octupole plasmon resonance improves light enhancement by a metal nanodimer

Sagar Sehrawat*, Andriy Shevchenko

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
27 Downloads (Pure)

Abstract

Metal nanoparticles are extensively used in science and technology to resonantly confine and enhance optical fields. Highest enhancement factors are achieved in nanosized gaps of metal dimers. It is commonly assumed that higher-order plasmon resonances, such as electric quadrupole and octupole, are in nanoparticles much weaker than a dipole resonance. Indeed, in the classical multipole expansion that deals with the scattered fields, these “dark” multipoles can be invisible. In this work, we show that an octupole resonance in a metal nanodimer can lead to a substantially larger field enhancement than a dipole resonance. The effect is explained by the fact that the near-field enhancement provided by the excited electric currents can be strong when the excitation is dark. This finding extends the design principles of a plasmonic nanostructure toward higher-order multipoles that, being naturally narrowband, can be useful for a variety of applications, especially in plasmonic sensing and detection.

Original languageEnglish
Pages (from-to)3432-3435
Number of pages4
JournalOptics Letters
Volume49
Issue number12
DOIs
Publication statusPublished - 15 Jun 2024
MoE publication typeA1 Journal article-refereed

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