Optical encryptions and decryptions based on all-optical shift register

In this paper, we proposed an optical encryption /decryption system based on all-optical shift register. The key used for encryption and decryption is an all-optical pseudorandom bit sequence (PRBS). By analysing the performance of the core functional unit of this system, which is composed of SOA-based logic XOR and all-optical clocked D flip-flops, we demonstrated the system's capability of producing stable optical PRBS signals, encrypting/decrypting the optical signals.