Study for Broad-Band Chaotic Generator Using Semiconductor Lasers in Secure Optical Communications

最近，人们发现半导体激光器的调制带宽被不同激光器的强光注入极大地提高了。在利用半导体激光器的混沌保密通信系统中，混沌载波的最大频率对数据传输速率起着重要的作用。混沌载波频率与半导体激光器的调制带宽密切相关。因此，在混沌保密光通信中，使用高调制带宽的半导体激光器是必不可少的。然而，对调制带宽提高的机理研究较少。在这项研究中，我们对强光注入半导体激光器的调制带宽机制进行了广泛的研究。此外，我们还研制了一种基于混沌半导体激光器和强光注入的宽带混沌产生器，用于硬件相关保密光通信…提出了具有光反馈的半导体激光器混沌产生器的模型，并用速率方程建立了系统的数学模型。通过数值模拟，通过在半导体激光器中引入强光注入，将没有强光注入的混沌截止载波频率从2.7 GHz扩展到7.0 GHz。在理论研究的基础上，我们研制了一种由强光注入多量子阱半导体激光器构成的混沌发生器。注入比大于孤子激光输出功率的30%。在该系统中，对于3 GHz的孤立混沌载波频率，我们可以获得9 GHz的带宽。对于DFB半导体激光器，没有光学注入的混沌发生器频率从3 GHz扩展到14 GHz。在此基础上，对宽带混沌发生器中的混沌同步进行了数值研究。根据这一数值研究，我们成功地实现了宽带混沌发生器之间的混沌同步。此外，我们还数值地实现了孤立混沌载波上的信息传输。较少

Recently, it has been discovered that the modulation bandwidth of semiconductor laser is greatly enhanced by a strong optical injection from a different laser. In chaotic secure communication systems using semiconductor lasers, the maximum chaotic carrier frequency plays an important role for data transmission rate. The chaotic carrier frequency is closely related to the modulation bandwidth of semiconductor lasers. Therefore the usage of semiconductor lasers with high modulation bandwidth is essential in chaotic secure optical communications. However, little study has been performed for the mechanism of the enhancement of the modulation bandwidth. In this study, we performed an extensive research for the mechanism for the modulation bandwidth in semiconductor lasers with strong optical injection. Also, we developed a broad-band chaotic generators using chaotic semiconductor lasers with strong optical injection for the purpose of hardware-dependent secure optical secure communications … More with high data-transmission rate.We have proposed the model for the chaotic generator of semiconductor lasers with optical feedback and formulated the systems by the rate equations. By the numerical simulations, the cut-off chaotic carrier frequency of 2.7 GHz without strong optical injection to a semiconductor laser is expanded to 7.0 GHz by the introduction of strong optical injection to the laser. Based on the theoretical investigation, we have developed a chaotic generator consisting of a MQW semiconductor laser with strong optical injection. The injection ratio was over 30 % of the solitary laser output power. In this system, we could obtain 9 GHz bandwidth for the solitary chaotic carrier frequency of 3 GHz. For the case of a DFB semiconductor laser, the chaotic generator frequency of 3 GHz without optical injection is expanded up to 14 GHz. Based on this research, we have done numerical study for chaos synchronization in the broadband chaotic generators. According to this numerical study, we have successfully performed chaos synchronization between the broadband chaotic generators. Also we have numerically succeeded a message transmission over the solitary chaotic carrier frequency. Less