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.

翻译：基于公共信号诱导的光反馈半导体激光器同步技术，为具有信息论安全性和高速率潜能的物理层密钥分发提供了可行方案。当前面临的主要挑战是：如何在确保安全性的操作参数空间内，通过缩短同步恢复时间来提升密钥生成速率。本研究提出采用开环同步方案，利用波长可调谐的多段式分布式布拉格反射（DBR）激光器实现物理层密钥分发。实验表明，该同步机制对光栅段电流和相位段电流两个操作参数具有敏感性。进一步研究发现，通过对两个电流参数之一的直接调制，可实现快速波长键控同步。与闭环同步相比，同步恢复时间降低了一个数量级。实验验证表明，在160公里光纤距离上实现了5.98 Mbit/s的最终密钥速率。因此，快速可调谐多段式半导体激光器为基于激光同步的高速物理层密钥分发开辟了新途径。