Secure Optical Communication System Based on ASE Noise with No Need for Key Distribution

Abstract

We propose and experimentally demonstrate a stable secure optical communication system with no need for secure key distribution. In this scheme, the amplified spontaneous emission (ASE) noise is used as the optical carrier to hide the signal both in time and frequency domain. The coherence length of the ASE noise is pretty short so that it is extremely difficult for an eavesdropper to intercept the signal. Only one Mach-Zehnder interferometer exists in the receiver, and there is no need for the receiver to match the optical delay. By this way, the optical delay and the polarization fluctuation caused by the environment can be automatically counteracted in the returning path. Therefore, no key distribution is required, and the optical delay value can be changed dynamically as a secret key in the receiver. In our experiment, 1Gb/s encrypted on-off keying signal is securely transmitted over 25km standard single mode fiber and dispersion compensation fiber.