High Speed Bidirectional Dual-Channel Chaos Secure Communication Based On Semiconductor Ring Lasers

With the rapid development of information society, chaos secure communication system with a high rate, high security, multi-channel has become a hot topic. The optical chaos secure system based on semiconductor lasers own unique advantages, such as wide bandwidth, high complexity and good compatibility among the existing fiber communication systems and so on. So far, a series of long-distance chaos secure communication system have been studied, and series meaningful research results are achieved. Recently, researchers propose a new type of semiconductor lasers: the semiconductor ring lasers(SRLs). Compared with other types of semiconductor lasers, SRLs have a ring resonance cavity, no requiring facet or mirror reflection, and then have unique advantages as high integration, small size, low threshold, and low power consumption. Especially, SRLs may excite two opposite transmission modes, namely clockwise(CW) and counterclockwise(CCW) patterns, and provide the possibility for the dual-channel parallel communication. At present, current optical chaos secure communication schemes mainly focus on unidirectional and singlechannel way. The capacity of information transmission in such scheme is still relatively low due to the limitation of the response bandwidth of laser. Therefore, the investigation of highspeed bidirectional dual-channel chaos secure communication using SRLs has important significance.This thesis proposes a novel high speed bidirectional dual-channel chaos secure communication system based on SRLs. Firstly, the time delay signatures of chaotic outputs of CW and CCW patterns from a driving SRL(D-SRL) are suppressed using the double optical cross-feedback frame. Then, the chaotic outputs of D-SRL are injected into two response SRLs(R-SRLs) to drive corresponding CW and CCW patterns of R-SRLs being synchronized and bandwidth enhanced simultaneously. Thus, a bidirectional dual-channel chaos communication is built based on chaotic synchronization of the two R-SRLs. We theoretically investigated the chaotic characteristics of D-SRL under double optical crossfeedback and the chaotic synchronization features between two R-SRLs under different driving conditions. Results show that the time delay signatures of CW and CCW patterns of D-SRL could be effectively hidden under proper feedback conditions. The bandwidth of CW and CCW patterns of D-SRL could be enhanced significantly. Furthermore, high-quality isochronous synchronization between two R-SRLs can be realized by choosing appropriate injection strength and detuning frequency between D-SRL and R-SRLs. Finally, the communication performances of bidirectional dual-channel chaos secure communication based on this proposed system are preliminarily examined and discussed, and the simulated results demonstrate that for 10 Gbit/s message, the Q factor of decoded message could be maintained above 6 after 10 kilometers transmission.Next, another dual-channel secure communication scheme based on SRLs with optoelectronic feedback is investigated. In this scheme, the complex chaos signals of D-SRL CW and CCW patterns are firstly generated by using optoelectronic feedback. Secondly, the chaos signal is injected into an R-SRL with an optoelectronic way, then causes the chaotic synchronization between the D-SRL and R-SRL, and finally realizes the high rate and dualchannel secure communication between D-SRL and R-SRL. The chaos characteristic of DSRL and the synchronization characteristic between D-SRL and R-SRL are both investigated theoretically and numerically under different conditions. The results show that the D-SRL can produce good CW and CCW patterns chaotic signal with appropriate optoelectronic feedback. The good chaotic synchronization can achieved under proper signal injection. Finally, the 10 Gbit/s message dual-channel secure communication is demonstrate numerically.