The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields

TL;DR

This paper introduces the optical chirality flux as a new far-field measurable quantity that effectively characterizes the magnitude and handedness of chiral near fields around nanostructures, aiding in the optimization of chiral light-matter interactions.

Contribution

It formulates the conservation law of optical chirality in lossy dispersive media and identifies the optical chirality flux as a practical far-field probe for chiral near fields.

Findings

Optical chirality flux provides detailed information on chiral near fields.

It offers advantages over circular dichroism spectroscopy.

The flux is linked to the conservation law of optical chirality.

Abstract

To optimize the interaction between chiral matter and highly twisted light, quantities that can help characterize chiral electromagnetic fields near nanostructures are needed. Here, by analogy with Poynting's theorem, we formulate the time-averaged conservation law of optical chirality in lossy dispersive media and identify the optical chirality flux as an ideal far-field observable for characterizing chiral optical near fields. Bounded by the conservation law, we show that it provides precise information, unavailable from circular dichroism spectroscopy, on the magnitude and handedness of highly twisted fields near nanostructures.