Nonlinear circular dichroism in Mie-resonant nanoparticle dimers

TL;DR

This paper develops a theory for nonlinear circular dichroism in Mie-resonant dielectric nanoparticle dimers, demonstrating enhanced second-harmonic generation signals and confirming predictions with experimental results.

Contribution

The paper introduces a comprehensive multipolar hybridization theory for nonlinear CD in dielectric nanoparticle dimers, supported by experimental validation.

Findings

Nonlinear circular dichroism observed in second-harmonic generation.

Enhanced SHG signals due to multipolar resonances.

Experimental confirmation of theoretical predictions.

Abstract

We study nonlinear response of a dimer composed of two identical Mie-resonant dielectric nanoparticles illuminated normally by a circularly polarized light. We develop a general theory describing hybridization of multipolar modes of the coupled nanoparticles, and reveal nonvanishing nonlinear circular dichroism (CD) in the second-harmonic generation (SHG) signal enhanced by the multipolar resonances in the dimer provided its axis is oriented under an angle to the crystalline lattice of the dielectric material. We present experimental results for this SHG-CD effect obtained for the AlGaAs dimers placed on an engineered substrate which confirm the basic prediction of our general multipolar hybridization theory.