Optical properties of a two-nanospheroid cluster: analytical approach

TL;DR

This paper provides an analytical study of the optical properties of a nano-antenna composed of two metallic nanospheroids, revealing three plasmonic modes and their excitation mechanisms, with formulas for key optical characteristics.

Contribution

It introduces an analytical approach to characterize three plasmonic modes in a two-nanospheroid cluster and their excitation by different light sources.

Findings

Identification of three plasmonic modes in nanospheroid clusters

Analytical expressions for absorption and scattering cross-sections

Enhanced local fields and radiative decay rates near the nano-antenna

Abstract

Optical properties of a plasmonic nano-antenna made of two metallic nanospheroids (prolate or oblate) are investigated analytically in quasistatic approximation. It is shown that in clusters of two nanospheroids, three types of plasmonic modes can be present. Two of them can be effectively excited by a plane electromagnetic wave, while the third one can be effectively excited only by a nanolocalized light source (an atom, a molecule, a quantum dot) placed in the gap between the nanoparticles. Analytical expressions for absorption and scattering cross-sections, enhancement of a local field, and radiative decay rate of a dipole source placed near such a nano-antenna are presented and analyzed.