Core-Shell Nanoparticle Resonances in Near-Field Microscopy Revealed by Fourier-demodulated Full-wave Simulations

TL;DR

This paper uses Fourier-demodulated full-wave simulations to analyze the complex near-field optical responses of core-shell nanoparticles, revealing resonance shifts and enhanced scattering that improve understanding of nanoscale optical interactions.

Contribution

It introduces a detailed simulation approach that accurately models the near-field responses of core-shell nanoparticles, advancing the theoretical understanding of their optical behavior.

Findings

Core-shell nanoparticles show unexpected resonance shifts.

Enhanced scattering driven by core and shell properties.

Refined framework for predicting nanostructure optical signatures.

Abstract

We present a detailed investigation of the near-field optical response of core-shell nanoparticles using Fourier-demodulated full-wave simulations, revealing significant modifications to established contrast mechanisms in scattering-type scanning near-field optical microscopy (s-SNOM). Our work examines the complex interplay of geometrical and optical resonances within core-shell structures. Using a finite element method (FEM) simulation closely aligned with the actual s-SNOM measurement processes, we capture the specific near-field responses in these nanostructures. Our findings show that core-shell nanoparticles exhibit unexpected distinct resonance shifts and massively enhanced scattering driven by both core and shell properties. This investigation not only advances the understanding of near-field interactions in complex nanosystems but also provides a refined theoretical framework to accurately predict the optical signatures of nanostructures with internal heterogeneity.