title: Photonic measures of helicity: optical vortices and circularly polarized reflection.
abstract: For both paraxial and nonparaxial light, numerous electromagnetic quantities are expressible in terms of photon annihilation and creation operators. Accordingly, measures of energy, angular momentum, and chirality 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, with pure circular polarization giving maximal values. Measures of orbital angular momentum are determined by a sum of corresponding number operators. Analysis of the electric and magnetic fields in the reflection of circular polarizations reveals regions of prominent chiral interference.
authors.affiliation: School of Chemistry, University of East Anglia, Norwich, UK.
authors.forename: Matt M
authors.initials: MM
authors.lastname: Coles
authors.forename: David L
authors.initials: DL
authors.lastname: Andrews