Coexistence of High-Speed Physical-Layer Key Distribution and Secure Data Transmission in Fiber

Physical-layer secure key distribution (PLSKD) exploiting channel reciprocity and randomness is promising for data security enhancement in fiber, offering an endogenous high key generation rate (KGR) up to Gb/s. The PLSKD provides the integration possibility of key generation and data transmission within the same fiber channel. The coexistence schemes of PLSKD and secure data transmission in fibers are proposed using wavelength division multiplexing (WDM), and full-duplex transmission at the same wavelength. The coexistence schemes are experimentally demonstrated with a 3.4 and 3.25 Gb/s PLSKD, where the encrypted data rate is 15.7 Gb/s, over a 20 km standard single-mode fiber (SSMF) using WDM or full-duplex respectively. The effects of channel spacing using WDM and trade-offs between PLSKD and secure data transmission using full-duplex are fully analyzed. The proposed secure data transmission with PLSKD is classical and fully compatible with current fiber infrastructures.