Constructing a chiral dipolar mode in an achiral nanostructure

TL;DR

This paper demonstrates how to excite a chiral dipolar electromagnetic mode in an achiral silicon nanoparticle using tailored illumination, revealing its emission properties and dependence on wavelength and angular momentum.

Contribution

It introduces a method to generate chiral modes in achiral nanostructures without chiral design, using specific excitation techniques and analyzing their emission characteristics.

Findings

Successful excitation of chiral dipolar mode in achiral silicon nanoparticle.

Wavelength-dependent emission properties of the chiral mode.

Measurement of spin and orbital angular momentum in the emission.

Abstract

We discuss the excitation of a chiral dipolar mode in an achiral silicon nanoparticle. In particular, we make use of the electric and magnetic polarizabilities of the silicon nanoparticle to construct this chiral electromagnetic mode which is conceptually similar to the fundamental modes of 3D chiral nanostructures or molecules. We describe the chosen tailored excitation with a beam carrying neither spin nor orbital angular momentum and investigate the emission characteristics of the chiral dipolar mode in the helicity basis, consisting of parallel electric and magnetic dipole moments, phase shifted by $\pm \pi/2$. We demonstrate the wavelength dependence and measure the spin and orbital angular momentum in the emission of the excited chiral mode.