Surface angular momentum of light beams

Abstract

Traditionally, the angular momentum of light is calculated for "bullet-like" electromagnetic wave packets, although in actual optical experiments "pencil-like" beams of light are more commonly used. The fact that a wave packet is bounded transversely and longitudinally while a beam has, in principle, an infinite extent along the direction of propagation, renders incomplete the textbook calculation of the spin/orbital separation of the angular momentum of a light beam. In this work we demonstrate that a novel, extra surface part must be added in order to preserve the gauge invariance of the optical angular momentum per unit length. The impact of this extra term is quantified by means of two examples: a Laguerre-Gaussian and a Bessel beam, both circularly polarized.

14 pages, 1 figure

References in corpus (7)

• Conservation of Angular Momentum, Transverse Shift, and Spin Hall Effect in Reflection and Refraction of Electromagnetic Wave Packet
• Role of beam propagation in Goos-Hänchen and Imbert-Fedorov shifts
• Angular Momenta and Spin-Orbit Interaction of Nonparaxial Light in Free Space
• Optical nanoprobing via spin-orbit interaction of light
• On the experimental investigation of the electric and magnetic response of a single nano-structure
• Optical forces and torques in non-uniform beams of light
• Angular momentum of non-paraxial light beam: Dependence of orbital angular momentum on polarization

Cited by in corpus (8)

• Transverse and longitudinal angular momenta of light
• Conservation of the spin and orbital angular momenta in electromagnetism
• The Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses
• Higher-order modes of vacuum-clad ultrathin optical fibers
• Measurement of Optical Orbital and Spin Angular Momentum: Implications for Photon Angular Momentum
• Superkicks and the photon angular and linear momentum density
• A still unsettled issue in the nucleon spin decomposition problem : On the role of surface terms and gluon topology
• Properties of the Poynting vector for invariant beams: negative propagation in Weber beams