Physical-layer key distribution using synchronous complex dynamics of DBR semiconductor lasers

TL;DR

This paper demonstrates a novel open-loop synchronization method for wavelength-tunable DBR semiconductor lasers, enabling high-rate physical-layer key distribution with significantly reduced recovery time and secure communication over long distances.

Contribution

Proposes and experimentally validates open-loop synchronization of multi-section DBR lasers for fast, secure physical-layer key distribution, surpassing previous closed-loop methods in speed and security.

Findings

Achieved a key rate of 5.98 Mbit/s over 160 km fiber

Shortened synchronization recovery time by an order of magnitude

Demonstrated secure high-rate key distribution using laser synchronization

Abstract

Common-signal-induced synchronization of semiconductor lasers with optical feedback inspired a promising physical key distribution with information-theoretic security and potential in high rate. A significant challenge is the requirement to shorten the synchronization recovery time for increasing key rate without sacrificing operation parameter space for security. Here, open-loop synchronization of wavelength-tunable multi-section distributed Bragg reflector (DBR) lasers is proposed as a solution for physical-layer key distribution. Experiments show that the synchronization is sensitive to two operation parameters, i.e., currents of grating section and phase section. Furthermore, fast wavelength-shift keying synchronization can be achieved by direct modulation on one of the two currents. The synchronization recovery time is shortened by one order of magnitude compared to close-loop synchronization. An experimental implementation is demonstrated with a final key rate of 5.98 Mbit/s over 160 km optical fiber distance. It is thus believed that fast-tunable multi-section semiconductor lasers opens a new avenue of high-rate physical-layer key distribution using laser synchronization.