Transverse rotation of the momentary field distribution and the orbital angular momentum of a light beam

TL;DR

This paper derives an analytical criterion linking the transverse oscillations of a light beam's electromagnetic field to its rotation and orbital angular momentum, enhancing understanding of beam structure.

Contribution

It introduces a new analytical criterion connecting field oscillations, rotation, and orbital angular momentum in light beams.

Findings

Oscillations are coupled with rotation around the beam axis.

The criterion relates oscillations to the orbital angular momentum.

Provides a deeper understanding of beam transverse structure.

Abstract

The transverse beam pattern, usually observed in experiment, is a result of averaging the optical-frequency oscillations of the electromagnetic field distributed over the beam cross section. An analytical criterion is derived that these oscillations are coupled with a sort of rotation around the beam axis. This criterion appears to be in direct relation with the usual definition of the beam orbital angular momentum.