### Abstract

Original language | English |
---|---|

Pages (from-to) | S7-S16 |

Journal | Journal of Optics B: Quantum and Semiclassical Optics |

Volume | 4 |

Issue number | 2 |

DOIs | |

Publication status | Published - Apr 2002 |

### Fingerprint

### Keywords

- angular momentum
- electromagnetic theory
- photonics
- optics

### Cite this

*Journal of Optics B: Quantum and Semiclassical Optics*,

*4*(2), S7-S16. https://doi.org/10.1088/1464-4266/4/2/361

}

*Journal of Optics B: Quantum and Semiclassical Optics*, vol. 4, no. 2, pp. S7-S16. https://doi.org/10.1088/1464-4266/4/2/361

**Optical angular-momentum flux.** / Barnett, S.M.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Optical angular-momentum flux

AU - Barnett, S.M.

PY - 2002/4

Y1 - 2002/4

N2 - We introduce the angular-momentum flux as the natural description of the angular momentum carried by light. We present four main results: (i) angular-momentum flux is the flow of angular momentum across a surface and, in conjunction with the more familiar angular-momentum density, expresses the conservation of angular momentum. (ii) The angular-momentum flux for a light beam about its axis (or propagation direction) can be separated into spin and orbital parts. This separation is gauge invariant and does not rely on the paraxial approximation. (iii) Angular-momentum flux can describe the propagation of angular momentum in other geometries, but the identification of spin and orbital parts is then more problematic. We calculate the flux for a component of angular momentum that is perpendicular to the axis of a light beam and for the field associated with an electric dipole. (iv) The theory can be extended to quantum electrodynamics.

AB - We introduce the angular-momentum flux as the natural description of the angular momentum carried by light. We present four main results: (i) angular-momentum flux is the flow of angular momentum across a surface and, in conjunction with the more familiar angular-momentum density, expresses the conservation of angular momentum. (ii) The angular-momentum flux for a light beam about its axis (or propagation direction) can be separated into spin and orbital parts. This separation is gauge invariant and does not rely on the paraxial approximation. (iii) Angular-momentum flux can describe the propagation of angular momentum in other geometries, but the identification of spin and orbital parts is then more problematic. We calculate the flux for a component of angular momentum that is perpendicular to the axis of a light beam and for the field associated with an electric dipole. (iv) The theory can be extended to quantum electrodynamics.

KW - angular momentum

KW - electromagnetic theory

KW - photonics

KW - optics

UR - http://dx.doi.org/10.1088/1464-4266/4/2/361

U2 - 10.1088/1464-4266/4/2/361

DO - 10.1088/1464-4266/4/2/361

M3 - Article

VL - 4

SP - S7-S16

JO - Journal of Optics B: Quantum and Semiclassical Optics

JF - Journal of Optics B: Quantum and Semiclassical Optics

SN - 1464-4266

IS - 2

ER -