Free-space communication through turbulence: a comparison of plane-wave and orbital-angular-momentum encodings

TL;DR

This paper compares plane-wave and orbital-angular-momentum encodings for free-space communication through turbulence, finding that plane-wave modes are more robust in high Fresnel number systems, impacting quantum key distribution.

Contribution

It introduces a system encoding onto plane-wave modes and demonstrates their superiority over OAM modes in turbulent atmospheric conditions.

Findings

Plane-wave modes outperform OAM modes in turbulence.

High Fresnel number systems favor plane-wave encoding.

Implications for quantum key distribution systems.

Abstract

Free-space communication allows one to use spatial mode encoding, which is susceptible to the effects of diffraction and turbulence. Here, we discuss the optimum communication modes of a system while taking such effects into account. We construct a free-space communication system that encodes information onto the plane-wave (PW) modes of light. We study the performance of this system in the presence of atmospheric turbulence, and compare it with previous results for a system employing orbital-angular-momentum (OAM) encoding. We are able to show that the PW basis is the preferred basis set for communication through atmospheric turbulence for a large Fresnel number system. This study has important implications for high-dimensional quantum key distribution systems.