A new type of bidirectional long distance optical fiber chaotic secure communication system

Based on the chaotic synchronization of two response semiconductor lasers (RLs) under the injection from a common chaotic signal of a drive laser (DL), a new type of secure communication system, which allows bidirectional and long-distance information transmissions, is proposed. A corresponding theoretical model is established to study the bidirectional transmission performance, security performance and the system performance under different transmission distances. The results show that when two RLs receive chaotic light injected from a DL, the chaotic outputs of two RLs achieve a fairly good isochronal synchronization without any time delay, while there is a big difference between the signals of RLs and the signal of DL; the system owns high security level after having analyzed the various ways from which eavesdropper may obtain message; if the ordinary single mode optical fiber is used as a transmission channel, the Q factor of decoded message can reach more than 6 after a propagation over 50km; if the dispersion-shifted fiber is employed, the Q factor of decoded message can still reach more than 6 after a propagation over 200km.