Transverse energy flow and the "running" behaviour of the instantaneous field distribution of a light beam

TL;DR

This paper generalizes the relationship between the instantaneous field pattern's motion in a light beam and the transverse energy flow, establishing a link between observable energy flow and the 'running' behavior of the field pattern.

Contribution

It extends previous findings by showing that any directed motion of the instantaneous field pattern corresponds to transverse energy flow, providing a new geometric and kinematic perspective.

Findings

Directed motion of the instantaneous field pattern relates to transverse energy flow.

Transverse orbital flow density characterizes the 'running' behavior of the field.

The work generalizes the connection between field pattern dynamics and energy flow.

Abstract

It is known that the orbital angular momentum of a paraxial beam is related to the rotational motion of the instantaneous field pattern representing the electric field optical-frequency oscillations [arXiv:0812.0888; J. Opt. A: Pure Appl. Opt 11, 094004, (2009)]. Now this conclusion is generalized: any identifiable directed motion of the instantaneous 2D pattern of the field oscillation ("running" behaviour of the instant oscillation pattern) corresponds to the transverse energy flow in the experimentally observable time-averaged field. The transverse orbital flow density can be treated as a natural geometric and kinematic characteristic of this running behaviour.