Investigation On Bidirectional Dual-channel Long-distance Chaos Secure Communication Based On1550Nm Vertical-cavity Surface-emitting Lasers

The development of technology is the improvement of an information society. As the society advances, requirements on the speed, capacity and security of communication increase day by day, making new secure communication system with high speed, large capacity and high degree of security a hot topic. Due to these features of chaos signal as high complexity, unpredictability, easy to copy and implement, it can be used as a carrier of information transmission to achieve chaotic security communication. The optical chaotic system consists of vertical-cavity surface-emitting lasers(VCSELs) has many unique beneficial features, namely, broad bandwidth, low attenuation, high complexity, single longitudinal mode output, low threshold current, easy to large-scale integration and high-coupling efficiency to optical fiber. Thus, the VCSELs can be used in optical fiber communication systems to achieve high-speed long-distance chaotic secure communication. Two linear polarization modes in VCSELs with appropriate parameters and initial conditions can be achieved. It makes the dual channel chaotic secure communication possible. In last a few years, investigations on optical chaos synchronization secure communication based on semiconductor were coming up. However, the study concerning bidirectional and dual-channel long-distance chaos secure communication system based on1550nm VCSELs is relatively lacking.In this paper, the basic theories of chaos synchronization, VCSELs and the impacts of fiber channel to chaos secure communication was briefly introduced. What’s more, a novel bidirectional and dual-channel long-distance chaos secure communication system based on1550nm-VCSELs was presented and investigated. The system consists of a driving1550nm-VCSEL and two responding1550nm-VCSELs. According to the chaos synchronization between two pairs of corresponding linear polarization modes in two1550nm-VCSELs subject to optical injection of common chaotic signals, a novel bidirectional and dual-channel long-distance chaos secure communication system is proposed. Furthermore, the chaotic synchronization characteristics, bidirectional dual-channel communication performance and the influences of the fiber channel on the message transmission are numerically investigated. The results show that, driven by a common chaotic signal generated from a driven VCSEL (D-VCSEL), two pairs of responding linear polarization modes in two response1550nm-VCSELs (R-VCSELs) can be synchronized completely and isochronally. Meanwhile, the synchronization coefficients between two pairs of responding linear polarization modes in D-VCSEL and R-VCSELs are low. As for the high quality chaos synchronization between two pairs of responding linear modes in two R-VCSELs, bidirectional and dual-channel chaos secure communication can be achieved. After adopting single mode polarization-maintaining fiber for2.5Gbit/s messages, the Q factor of the decryption signals after transmitting60km can be maintained more than6. While with dispersion-shifted polarization-maintaining fiber after transmitting200km the Q factor was achieved more than6. Therefore, the system can be applied to achieve bidirectional and dual-channel long-distance chaos secure communication.