Selective excitation of plasmons superlocalized at sharp perturbations of metal nanoparticles

¹ Shubnikov Institute of Crystallography of Russian Academy of Sciences - 119333 Moscow, Russia
² Institute of Automation and Electrometry of Russian Academy of Sciences - 630090 Novosibirsk, Russia

Received: 27 April 2015
Accepted: 3 June 2015

Abstract

Sharp metal corners and tips support plasmons localized on the scale of the curvature radius —superlocalized plasmons. We analyze plasmonic properties of nanoparticles with small and sharp corner- and tip-shaped surface perturbations in terms of hybridization of the superlocalized plasmons, which frequencies are determined by the perturbations shape, and the ordinary plasmons localized on the whole particle. When the frequency of a superlocalized plasmon gets close to that of the ordinary plasmon, their strong hybridization occurs and facilitates the excitation of an optical hot spot near the corresponding perturbation apex. The particle is then employed as a nano-antenna that selectively couples the free-space light to the nanoscale vicinity of the apex providing precise local light enhancement by several orders of magnitude.