When does nonlinear circular dichroism appear in achiral dielectric nanoparticles?

TL;DR

This paper provides a theoretical framework to determine when nonlinear circular dichroism appears in achiral dielectric nanoparticles, emphasizing the importance of symmetry and orientation, and offers a simple formula for prediction.

Contribution

It introduces a general and simple formula to predict the presence of nonlinear circular dichroism based on symmetry and orientation in dielectric nanostructures.

Findings

Circular dichroism depends on relative orientation, not just symmetry.

A simple formula can predict dichroism presence.

A comprehensive table of key cases is provided.

Abstract

Sometimes it appears, sometimes it does not. We present a theoretical study of circular dichroism in the second-harmonic signal of single dielectric nanostructures with different symmetries and noncentrosymmetric materials. We show that this effect is not fully identified only by macroscopic and lattice symmetries, but their relative orientation as well. Based on the cumbersome symmetry and modal analysis, we provide a general and very simple formula to determine whether the dichroism exists, and a table with the most significant cases.