Security enhancement for a DPSK telecommunication system using false data transmission

In this conference, we demonstrate a new communication system exhibiting a double security level. Information coding is based on differential phase shift keying of the light emitted from a highly coherent CW source. An imbalanced Mach-Zehnder interferometer whose time delay matches the bit duration is used to decode the data. Since the optical power is constant in the transmission link, security levels comparable with those obtained in coherence modulation may be achieved. To further enhance the security, a low coherent source is used to send false data down the transmission link. The discrimination between real and false signal is based on common mode rejection. A study of the signal to noise ratio achieved with this system is also discussed in this manuscript.