Characterization of vector diffraction-free beams

TL;DR

This paper introduces a new way to characterize vector diffraction-free beams using a constant unit vector, expanding the understanding of their properties and including previous beams as special cases.

Contribution

It proposes the use of a constant unit vector to fully characterize vector diffraction-free beams, revealing their dependence and unifying previous solutions.

Findings

Diffraction-free beams are characterized by a constant unit vector.

Previous diffraction-free beams are special cases within this framework.

The longitudinal component's dependence on the vector I is analyzed.

Abstract

It is observed that a constant unit vector denoted by $\mathbf I$ is needed to characterize a complete orthonormal set of vector diffraction-free beams. The previously found diffraction-free beams are shown to be included as special cases. The $\mathbf I$-dependence of the longitudinal component of diffraction-free beams is also discussed.