A full characterization of the polarization of vector light beams

TL;DR

This paper introduces a comprehensive method to characterize the polarization of general vector light beams, incorporating a new degree of freedom called the Stratton vector, which extends the traditional Stokes parameters for nonparaxial beams.

Contribution

It generalizes the polarization characterization by defining a natural coordinate system and introduces the Stratton vector as an additional degree of freedom for full polarization description.

Findings

The Stratton vector acts as an extra degree of freedom in polarization.

A phase factor with observable effects is identified in helicity states.

The approach enables complete polarization characterization of nonparaxial light beams.

Abstract

We present an approach to fully characterize the polarization of general vector light beams. When attempting to generalize the notion of Stokes parameters to nonparaxial light beams in momentum space, we find that the Jones function that determines the Stokes parameters through the Pauli matrices is defined over a natural coordinate system that is fixed by a constant unit vector, called the Stratton vector. We further show that the Pauli matrices represent the intrinsic degree of freedom of the polarization with respect to the natural coordinate system so that the Stratton vector acts as an additional degree of freedom that complements the intrinsic degree of freedom to fully characterize the polarization. As a consequence of the new degree of freedom, the Stratton vector, in helicity states, a phase factor that has observable physical effects is identified. Examples of its application to characterizing the state of polarization are also given.