The Research On Key Technologies Of Chaotic Optical Communication System Based On Semiconductor Ring Lasers

In recent years, the use of chaotic signals in secure optical communication systemas the optical carrier has attracted wide attentions. By adding appropriate freedisturbance terms, B class lasers including semiconductor lasers could operate onunstable state with optical chaotic output. As a special kind of semiconductor lasers,semiconductor ring lasers (SRLs) with ring resonant cavity offering lots of uniqueadvantages become a cutting-edge research topic. The use of the SRL in chaotic signalgeneration and synchronization system could simplify the system, improve reliability,and decrease power consumption effectively.In this thesis, the laser chaos theory has been described briefly. Based on thekinetic equations of the SRL, the key technologies of the chaotic opticalcommunication systems have been studied, which include the chaos generation andchaos synchronization in SRLs. The structure of this manuscript is organized asfollows:1. The overview of chaos. Chaos is a form of nonlinear phenomena, which issimilar to random phenomenon produced in some determined nonlinear system. In thisthesis, the evolution of chaos has been described, as well as laser chaos, chaossynchronization, chaos characteristics and the applications. Moreover, a briefintroduction of SRL’s structure and functions has been given. We also review thecurrent worldwide research work on chaos communication systems and SRLs.2. Laser chaos theory. Principles and classification of lasers have been discussed.The path to chaos and the mathematical analysis methods that consist of the strangeattractor and the Lyapunov exponent have been summarized. Moreover, a briefintroduction of three common ways to generate laser chaotic signals and the laserchaos synchronization theory has been demonstrated. Afterwards, we focus on thedynamics of the SRL model.3. Three models for chaotic signals generation in SRLs. In this paper, we studythe operating states of the SRL disturbed by optoelectronic feedback, optical injection,and optical feedback. Through the simulation analysis on the disturbed parameters, chaotic signal in a SRL with three way disturbances can be generated respectively.4. Based on our previous work, the bandwidth enhanced chaos generation in aSRL is also obtained by narrowband chaotic light injection.5. Chaos synchronization scheme based on two SRLs. The chaotic signal,generated in a SRL with optical feedback as the transmitter, is injected into anotherSRL with the same parameters as the receiver. With a strong chaotic signal injectionfrom the transmitter to the receiver, the original oscillation of the receiver is disturbedand locked by the chaotic oscillation of the transmitter SRL. After injection locking,the generalized synchronization between the drive and the response SRLs is achieved.By using the autocorrelation function to evaluate the results, the chaos synchronizationprocess is optimized.Finally, we make a conclusion of the development, applications and future of thechaotic SRL in chaotic optical communication systems.