Angular momentum conservation in counter-propagating vectorially structured light

Abstract

It is well-known that electric spin angular momentum and electric orbital angular momentum are conserved under paraxial propagation of travelling waves in free-space. Here we study the electric and magnetic angular momentum in counter-propagating waves and show both theoretically and experimentally that neither component alone is conserved except in special cases. We attribute this non-conservation to spin-spin and orbit-orbit coupling between the electric and magnetic fields. This work generalises previous findings based on travelling waves, explains the apparent spin-orbit coupling in counter-propagating paraxial light, and broadens our understanding of angular momentum conservation in arbitrary structured light waves.

References in corpus (5)

• Chiral nanophotonic waveguide interface based on spin-orbit coupling of light
• Angular Momenta and Spin-Orbit Interaction of Nonparaxial Light in Free Space
• Orbital-to-Spin Angular Momentum Conversion Employing Local Helicity
• Note on the helicity decomposition of spin and orbital optical currents
• Spin-orbit interactions in optically active materials

Cited by in corpus (6)

• Nonseparable states of light: From quantum to classical
• Gouy-phase-mediated propagation variations and revivals of transverse structure in vectorially structured light
• Kelvin's Chirality of Optical Beams
• COMET: Clustering Observables Modelled by Emulated perturbation Theory
• Quantum structured light: Non-classical spin texture of twisted single-photon pulses
• Quantum theory of photonic vortices and quantum statistics of twisted photons