Directions In Optical Angular Momentum

TL;DR

This paper explores the fundamental measures of optical angular momentum, including spin and orbital components, in both paraxial and non-paraxial light, highlighting their quantum photon-based interpretations and chiral interactions.

Contribution

It introduces a unified photon-based framework for understanding electromagnetic angular momentum and analyzes chiral interactions in reflected circular polarizations.

Findings

Photon-based measures of angular momentum are consistent for all light regimes.

An infinite hierarchy of spin measures depends on helicity mode differences.

Regions of strong chiral interaction are identified in interference patterns.

Abstract

For paraxial and non-paraxial light, numerous measures of electromagnetic attribute are expressible in terms of photon annihilation and creation. Accordingly, energy, angular momentum and chirality measures acquire a consistent interpretation. From the photonic nature of light, it emerges that an infinite hierarchy of spin-type measures depend on a difference in number operators for modes of opposing helicity, pure circular polarization giving maximal values. Measures of orbital angular momentum are determined by a sum of corresponding number operators. By analysis of electric and magnetic features in the reflection of circular polarizations, regions of prominent chiral interaction in the interference are identified.