Securing Data in Multimode Fibers by Exploiting Mode-Dependent Light Propagation Effects

TL;DR

This paper demonstrates a novel physical-layer security method in multimode fiber optical communication, using mode-dependent effects and structured light to secure data against eavesdroppers, significantly increasing secure data throughput.

Contribution

It introduces a new approach leveraging mode-dependent light propagation effects for secure data transmission in multimode fibers, validated through experimental implementation.

Findings

Secure data transmission is achieved with a factor of 538 increase in secure data.

The method effectively prevents eavesdropper decoding in a real scenario.

Exploiting modal effects opens new security perspectives in optical communications.

Abstract

Multimode fibers hold great promise to advance data rates in optical communications but come with the challenge to compensate for modal crosstalk and mode-dependent losses, resulting in strong distortions. The holographic measurement of the transmission matrix enables not only correcting distortions but also harnessing these effects for creating a confidential data connection between legitimate communication parties, Alice and Bob. The feasibility of this physical-layer-security-based approach is demonstrated experimentally for the first time on a multimode fiber link to which the eavesdropper Eve is physically coupled. Once the proper structured light field is launched at Alice's side, the message can be delivered to Bob, and, simultaneously, the decipherment for an illegitimate wiretapper Eve is destroyed. Within a real communication scenario, we implement wiretap codes and demonstrate confidentiality by quantifying the level of secrecy. Compared to an uncoded data transmission, the amount of securely exchanged data is enhanced by a factor of 538. The complex light transportation phenomena that have long been considered limiting and have restricted the widespread use of multimode fiber are exploited for opening new perspectives on information security in spatial multiplexing communication systems.