Photonic-layer secure 56 Gb/s PAM4 optical communication based on common noise driven synchronous private temporal phase en/decryption

All-optical encryption/decryption of DmPSK signals with key steganography for photonic layer security

In the 5th Generation Fixed networks (F5G) era, full-fiber-connected optical networks support emerging bandwidth-hungry services. However, optical networks are vulnerable to attack by tapping or other methods, which has been paid more and more attention in modern optical infrastructure. Therefore, optical Exclusive OR (XOR) encryption/decryption for advanced modulation formats used for F5G appears as one of the promising technologies to guarantee security. Some current solutions either leave potential security hazards because of the degenerate four-wave mixing and keys without special treatment or are cost-consuming due to employing multiple wavelengths and coherent receivers. In this paper, a novel all-optical encryption/decryption system for Differential m-Phase Shift Keying (DmPSK) signals occupying only a single wavelength with key steganography is proposed and simulated. The proposed system mainly consists of a generalized XOR (GXOR) part and a steganography part. We implement the GXOR part by the cascaded IQ Mach-Zehnder Modulators and the steganography part by the Equvilent-Phase-Shifted Super-Structured Fiber Bragg Grating (EPS-SSFBG). The numerical simulation results demonstrate that the GXOR implementation can achieve reconfigurable encryption/decryption of DQPSK (m = 4) or D8PSK (m = 8) signals merely with a single wavelength and a differential direct-detection receiver. And the EPS-SSFBG can enhance key security in a cost-efficient method as well. The system can work at the recorded bit rate of 260Gbps, which can be applied to enhance the photonic layer security in F5G and beyond.

High-speed chaos-based secure optical communications over 130-km multi-core fiber

Chaotic optical communication is of great significance for secure data transmission. Despite rapid development over the decades, high-speed (>100 Gbps) and long-distance (>100 km) chaotic optical communication in a single fiber is still full of challenges. Here, we propose and experimentally demonstrate high-speed and long-distance chaos-based secure optical communications using mutual injection of semiconductor lasers and space-division multiplexing (SDM) techniques. The encrypted signals are transmitted through all seven core channels of the multi-core fiber (MCF), which effectively expands the aggregate transmission capacity of a single fiber. A pair of source and synchronization devices based on mutual injection of semiconductor lasers are employed to effectively encrypt and decrypt signals. Chaos-based secure optical communications with 70-Gbps on-off keying (OOK) and 140-Gbps quadrature phase-shift keying (QPSK) signals over a 130-km MCF are successfully demonstrated in the experiment with favorable performance. The demonstration may pave the way for future ultrahigh capacity and ultra-long distance chaotic optical communications by fully exploiting multi-dimensional resources of light waves, including the spatial dimension.

Physical-layer security of optical communication based on chaotic optical encryption without an additional driving signal

We propose and numerically demonstrate a scheme for physical-layer security based on chaotic phase encryption, where the transmitted carrier signal is used as the common injection for chaos synchronization, so there is no need for additional common driving. To ensure privacy, two identical optical scramblers consisting of a semiconductor laser and a dispersion component are used to observe the carrier signal. The results show that the responses of the optical scramblers are highly synchronized but are not synchronized with the injection. By properly setting the phase encryption index, the original message can be well encrypted and decrypted. Moreover, the legal decryption performance is sensitive to the parameter mismatch, since it can degrade the synchronization quality. A slight drop in synchronization induces an evident deterioration in decryption performance. Therefore, without perfectly reconstructing the optical scrambler, the original message cannot be decoded by an eavesdropper.