Unified Treatment for Scattering, Absorption, and Photoluminescence of coupled Metallic Nanoparticles with Vertical Polarized Excitation

TL;DR

This paper explores the optical properties of vertically polarized coupled metallic nanoparticles, revealing unique coupling behaviors and peak shifts, validated by experimental comparisons, enhancing understanding of their scattering, absorption, and photoluminescence.

Contribution

It introduces a detailed model for vertical polarization coupling in metallic nanoparticles, highlighting three coupling coefficients and positive coupling terms, which differ from previous parallel polarization studies.

Findings

Blue-shifts of peaks with increasing coupling strength.

Validation of the model against experimental results.

Identification of three coupling coefficients for vertical polarization.

Abstract

Optical properties of coupled metallic particles (MNPs) have been widely reported due to their unique characteristics such as peak shift/splitting of the coupling spectra and electromagnetic enhancement at sub-wavelength scale, etc. In a previous work, we have investigated the coupling spectra of two coupled MNPs with parallel polarized excitation. In this study, we investigate the vertical polarization case in detail. Different from the parallel one, the vertical one has its unique properties: (a) three coupling coefficients; (b) positive coupling terms in the coupling equations; (c) blue-shifts of the peaks with the increasing coupling strength for identical MNPs spectra, including scattering, absorption, and photoluminescence. Comparison with published experimental results shows the validity of this model. This work provides a deeper understanding on the optical properties of coupled MNPs and is beneficial to relevant applications.