# Atmospheric turbulence does not change the degree of polarization of vector beams

## TL;DR

This paper introduces a theoretical framework showing that the degree of polarization of vector beams remains essentially unchanged during atmospheric propagation, regardless of turbulence or link type.

## Contribution

The authors develop a vectorial propagation model based on Fresnel equations that demonstrates the invariance of polarization degree in atmospheric conditions.

## Key findings

- Degree of polarization fluctuates insignificantly during propagation
- Change in DOP is on the order of 10^{-13} to 10^{-6}
- Results hold for both free-space and satellite links

## Abstract

We propose a novel theoretical framework to demonstrate vector beams whose degree of polarization does not change on atmospheric propagation. Inspired by the Fresnel equations, we derive the reflective and refractive field of vector beams propagating through a phase screen by employing the continuity of electromagnetic field. We generalize the conventional split-step beam propagation method by considering the vectorial properties in the vacuum diffraction and the refractive properties of a single phase screen. Based on this vectorial propagation model, we extensively calculate the change of degree of polarization (DOP) of vector beams under different beam parameters and turbulence parameters both in free-space and satellite-mediated links. Our result is that whatever in the free-space or satellite-mediated regime, the change of DOP mainly fluctuates around the order of $10^{-13}$ to $10^{-6}$, which is almost negligible.