25 Gb/s Physical Secure Communication Based on Temporal Spreading-Then-Random Phase Encryption

Ensuring high speed physical layer confidential data exchange in classical optical fiber channels is a critical challenge. In this letter, we experimentally demonstrated a physical secure optical communication system based on temporal spreading-then-random phase encryption scheme for secure transmission of 25 Gb/s intensity-modulated signal. Commercial low cost continuous-wave laser is employed as the optical source, and a chirped fiber Bragg grating followed by a phase modulator is utilized as a two-dimensional encryption module. Successful encryption and decryption of 25 Gb/s confidential data have been achieved by optimizing optical hardware parameters. The demonstrated system can combine the advantages of hardware and digital encryption, exhibiting great potential for providing physical layer security in future high-speed secure optical communication systems.