【作者】 刘姣；

【导师】 夏光琼；

【作者基本信息】 西南大学 ， 光学， 2010， 硕士

【摘要】 随着现代通信技术的不断发展,通信容量的不断增加,迫切需要研究开发具有高速、高保密性的新一代信息安全保密技术。近来,国际上对基于半导体激光器的光混沌及其在保密通信中应用的研究急剧升温,其技术的突破,必将对保密通信,特别是对军事保密通信产生革命性的影响。而相对于常规的边发射半导体激光器,作为新型量子阱半导体激光器的典型代表,垂直腔表面发射激光器(VCSLEs)具有低阈值电流,易于单纵模输出,大的调制带宽,易于集成等优点而受到人们的广泛关注。但目前人们对VCSELs的混沌同步特性及其在保密通信中的应用还缺乏深入的研究。本文针对VCSELs输出存在两个可能正交偏振态的特点,提出了两种实现单向双信道混沌通信系统方案：一种是基于平行光反馈和平行光注入下单向耦合VCSELs同步系统(简称平行系统),另一种是基于旋转光反馈和注入下单向耦合VCSELs系统(简称旋转系统)。对这两种系统中的两个正交线偏振模和总输出的混沌同步特性和混沌保密通信性能,内部参数失配对混沌同步质量的影响,以及电流变化时两个线偏振模式强度差值的变化等进行了深入研究。研究结果表明：在固定其他参数的情况下,在阈值电流附近时,平行系统中x模占主导地位,y模极弱,随着电流的增大,平行系统中两个线偏振模式的强度差值逐渐减小,而旋转系统中两个线偏振模式的强度始终相当；平行和旋转系统中两个线偏振模式和总输出之间都能实现完全同步,但是旋转系统对内部参数失配表现出更好的容忍性；在旋转系统中,分别加载在两个线偏振模式的传输信号能分别很好的解调出来,但是在平行系统中,当电流较小时(X模占主导地位),加载在x模式上的信号能很好的解调出来,而加载在y模式上的解调结果比较差。但随着电流的增大,y模逐渐增强,加载在y模式上的信号也能被成功解调。更多还原

【Abstract】 The security of the information transmission has become more and more important with the development of modern communication technology. In recent years, chaos and chaos synchronization of semiconductor lasers (SLs) has attracted much attention for its potential applications in secure communications. The break-though of this technology will bring about revolutions on secure communications, especially on martial secure communications. Compared to the conventional edge-emitting semiconductor lasers, the vertical-cavity surface-emitting lasers, as a new type and typical representative of quantum-well semiconductor lasers (VCSELs), exhibit several desirable characteristics such as a small threshold current, circular beam profile with narrow divergence, single longitudinal mode emission, wafer-scale testing and array capabilities. These great advantages have stimulated their development and use in applications. However, at present, the deep physical insight into chaos synchronization of VCSELs and its applications in secure communications are lacking.In this paper, two dual-channel chaotic synchronization configurations are proposed, taking the two orthogonal linear polarization (LP) states of the output of VCSELs into consideration. Two systems are constructed on the basis of two unidirectionally coupled VCSELs. One is called the polarization-preserved coupled system or the parallel coupled system for short, where a VCSEL subjected to polarization-preserved optical feedback is used as a transmitter and the other VCSEL subjected to polarization-preserved optical injection is used as a receiver. The other is called the polarization-rotated coupled system for short, where a VCSEL subjected to polarization-rotated optical feedback is used as a transmitter and the other VCSEL subjected to polarization-rotated optical injection is used as a receiver. The synchronization and communication performances of these two systems are numerically investigated. The results show that, the averaged intensity of x LP mode is always equivalent to that of y LP mode for the case of polarization-rotated optical feedback. But for the case of polarization-preserved optical feedback, the average intensities of these two LP modes are very different; the difference between the average intensities of two orthogonal LP modes becomes smaller with the current increase, In these two systems, complete synchronization can be achieved for each pair of corresponding LP modes and the total output, respectively. However, compared with the parallel coupled system system, the polarization-rotated coupled system has higher tolerance to mismatched parameters. Furthermore, in the polarization-rotated coupled system, the encoded messages can be successfully extracted for both of orthogonal LP modes. But in the parallel coupled system, only the encoded messages modulated on x LP mode can be successfully demodulated when the current is small. The message modulated on y LP mode cann’t be successfully extracted until the current increase to some value.更多还原