Influence of Atmospheric Turbulence on Optical Communications using Orbital Angular Momentum for Encoding

TL;DR

This paper experimentally investigates how atmospheric turbulence affects high-dimensional optical communication using orbital angular momentum modes, demonstrating capacity degradation and mitigation strategies relevant for quantum key distribution.

Contribution

It provides the first experimental analysis of turbulence effects on 11-dimensional OAM-based communication and proposes mitigation methods to improve channel robustness.

Findings

Turbulence degrades OAM channel capacity.

Increasing mode spacing mitigates turbulence effects.

Potential for high-dimensional QKD systems using current tech.

Abstract

We describe an experimental implementation of a free-space 11-dimensional communication system using orbital angular momentum (OAM) modes. This system has a maximum measured OAM channel capacity of 2.12 bits/photon. The effects of Kolmogorov thin-phase turbulence on the OAM channel capacity are quantified. We find that increasing the turbulence leads to a degradation of the channel capacity. We are able to mitigate the effects of turbulence by increasing the spacing between detected OAM modes. This study has implications for high-dimensional quantum key distribution (QKD) systems. We describe the sort of QKD system that could be built using our current technology.