基于混沌信号非相干光注入下两半导体激光器间的双向混沌通信

提出了基于同时受到一个驱动混沌信号非相干光注入的两个响应半导体激光器之间的混沌同步以实现双向保密通信的系统方案,并对系统的混沌同步特性以及两个响应激光器之间的内部参数失配对同步特性的影响进行了研究．研究结果表明：通过选取合适的系统参量,可以实现响应激光器与驱动激光器之间同步系数较小而两响应激光器之间达到高质量混沌同步;两响应激光器之间的内部参数失配对它们之间的同步性能虽然有一定的影响,但影响比较小．另外,本文还对两个2Gbit/s的信息在该系统中双向传输时的隐藏和解调效果以及系统的安全性进行了分析．     

多调制延时耦合半导体激光器的混沌同步与编码

数值研究了非相干光反馈与非相干光注入半导体激光器的多调制延时混沌同步,由于该系统是基于非相干注入的,所以不需要接收激光器的频率与发送激光器频率完全匹配。通过对非相干光反馈半导体激光器输出自相关函数的研究,发现在多调制延时系统中,延时标识可以被隐藏,这一特性可以提高系统的安全性,非常适用于混沌保密通信系统。分别利用混沌移位键控(CSK)及混沌隐藏(CMS)编码方法考查了单向耦合和双向耦合系统的通信性能。     

基于光电负反馈的激光混沌串联同步系统研究

提出了一种新的混沌中继系统，该系统基于光电负反馈的激光混沌串联同步.对该系统的同步性以及激光器内部参数失配对其同步性的影响进行了研究，并与基于光反馈的激光混沌串联同步系统进行了比较.研究结果表明：当系统参量满足一定条件时，该系统能实现完全同步；当激光器内部参数失配时，其混沌同步性会受到一定的影响，但该系统的混沌同步性对参数失配的容忍性要比基于光反馈的系统好得多.     

非相干光反馈与非相干光注入混沌同步通信系统仿真分析

本文对非相干光反馈与非相干光注入激光混沌同步保密通信系统进行了理论仿真研究.本系统为Pecora-Carroll混沌同步系统,基于Lang-Kobayashi速率方程,建立了发送激光器和接收激光器的理论模型.利用该模型分析了同步建立时间、同步误差,混沌键控编码/解码以及调制速率等特性.仿真结果表明系统具有很好的同步性能和保密性,混沌同步时间约为1 ns,混沌键控编码速率可达1 Gbit/s.研究结果对非相干光反馈与非相干光注入激光混沌同步保密通信系统的设计具有重要参考价值.     

基于光电反馈的激光混沌并联同步系统研究

提出了基于光电反馈的激光混沌并联同步方案,对可能存在的两种同步——广义同步和完全同步进行了研究,着重讨论了激光器内部参数失配对发射与接收激光器之间以及并联接收激光器之间同步特性的影响.研究结果显示：在一定范围内,同样的内部参数失配下,并联接收激光器之间的同步效果明显优于发射激光器与接收激光器之间的同步效果. 关键词： 半导体激光器 混沌同步 光电反馈 参数失配     

双路激光混沌复用系统的混沌同步及安全性能研究

针对一种新型的双路激光混沌复用系统, 建立相应的速率方程模型, 详细分析了两个主激光器的单个参数失配、多个参数同时失配、反馈强度差异以及频率失谐对混沌同步性能的影响, 并对此复用系统的安全性能和频谱性能进行了研究. 研究结果表明: 采用参数失配方案, 通过合理选择两个主激光器的参数, 可以保证两个主激光器之间的同步性能较差而两对主从激光器间实现高品质的混沌同步, 因此满足双路激光混沌复用的条件; 两个主激光器之间的参数失配对它们之间的同步性能影响较大, 然而对配对主从激光器间同步性能的影响并不明显, 进一步说明参数失配方案的有效性和可行性. 另外, 通过自相关函数和频谱分别分析混沌复用信号的时域和频域特征, 发现双路激光混沌复用系统可提供更高的安全性.     

基于光电反馈延迟的多点耦合混沌同步和通信

为了实现稳定的、可以同时同步的多点混沌通信,提出一种基于光电反馈延迟的双向混沌通信模型和多点耦合的混沌同步模型。在双向混沌通信模型中引入了时间延迟和混沌调制信息加密技术,增加了系统的安全性。数值分析了系统的同步性能、安全性能和通信性能,研究结果表明,系统能够历经很短的时间实现高质量的、稳定的同时同步,实现双向通信。并且延迟时间、信息信号功率、激光器光信号功率、相位的改变在其他参数匹配的情况下,不会降低系统的同步性能,即系统的信息信号功率、光信号功率、延迟时间、相位均可作为系统的密钥,提高系统的安全性。这种双向混沌通信模型可以拓展为符合一定拓扑结构的多点耦合混沌通信模型,并且推测随着网络中节点数的增加,系统的复杂度增加。     

链式互耦合半导体激光器的实时混沌同步

通过在互耦合外腔半导体激光器之间增加中继激光器,建立了一种链式互耦合半导体激光器混沌同步系统模型.理论分析了系统的实时混沌同步条件,数值研究了注入电流、互耦合条件、反馈条件等对系统实时混沌同步品质的影响,揭示了同步质量在反馈强度和互耦合强度二维参数空间的分布规律.结果表明:注入电流较大时,满足互耦合强度和反馈强度相同,互耦合延时和反馈延时相等,系统中所有激光器之间可同时实现稳定高品质实时混沌同步;中心激光器和边激光器之间的稳定实时混沌同步分布在在互耦合强度和反馈强度较小的区域以及互耦合强度和反馈强度相近的区域;边激光器之间由于同时接收到中心激光器实施的相同注入,能够较容易的实现稳定高品质的实时混沌同步.该系统可进一步扩展成为实现远距离的双向实时混沌同步或阵列激光器系统的实时混沌同步.     

基于半导体环形激光器的高速双向双信道混沌保密通信

提出了一种利用半导体环形激光器(SRLs)的新型高速双向、双信道混沌保密通信系统. 在该系统中, 首先利用交叉双光反馈对驱动激光器的顺时针模式和逆时针模式的混沌延时特征进行抑制. 然后将此混沌信号注入到一对响应激光器对应的顺时针模和逆时针模中, 以实现带宽的增强及混沌同步. 最后基于响应激光器之间的混沌同步, 实现高速率、双向、双信道的混沌保密通信. 通过对驱动激光器在交叉双光反馈作用下的混沌特性、以及响应激光器在不同条件下的同步特性进行了相关理论和仿真研究, 结果表明: 驱动激光器在合适的交叉双光反馈作用下可以产生延时特性被良好隐藏的顺时针模式和逆时针模式混沌信号; 在该混沌信号的注入下, 响应激光器输出的混沌信号带宽可以得到明显增强; 通过设置合适注入强度值和频率失谐值, 响应激光器之间可实现高质量的等时混沌同步. 最后, 对系统的双向、双信道混沌保密通信特性进行了讨论. 当10 Gbit/s信号传输距离为10 km时, 解调信息Q因子值仍可保持在6以上.     

采用混沌光注入实现混沌载波时延特征隐藏的研究

在混沌通信系统中,混沌载波的时延特征直接影响着通信系统的安全性,因此隐藏混沌载波的时延特征信息十分重要。本文基于外腔反馈式半导体激光器(ECSL)的单光注入结构,引入激光器参数失配,详细阐述了一种通过主从激光器参数失配来消除混沌信号时延特征的方法。利用自相关函数作为量化工具,对混沌信号的时延隐藏效果进行量化分析,数值研究了主从激光器间的参数失配对混沌信号时延消除的影响,并结合注入强度与频率失谐开展了进一步综合研究。研究结果表明:引入激光器参数失配对时延隐藏的效果影响显著,参数失配率在-0.4~0范围时有助于在从激光器混沌输出中隐藏主激光器外腔引入的反馈时延;而且,当主激光器注入强度在10ns-1~20ns-1范围内,主从激光器频率失谐控制在-20GHz附近时,信号时延隐藏效果最佳。因此,由此单混沌光注入系统产生的混沌信号可显著提高混沌载波的安全性,进而增强其潜在应用的性能。     

Chaos synchronization of optoelectronic coupled semiconductor lasers ring

In this paper, we propose a chaos synchronization configuration based on the optoelectronic coupled semiconductor lasers ring (OCSLR). The synchronization characteristics between semiconductor lasers (SLs) under unidirectional or bidirectional OCSLR are numerically investigated, and the influences of some typical internal and external mismatched parameters on synchronization are simultaneously discussed. The results show that, compared with a unidirectional OCSLR, the bidirectional OCSLR possesses better synchronization properties and robustness to the mismatched parameters. Moreover, the extraction of the encoded signals is preliminarily examined under the chaos shift keying scheme.     

Bidirectional chaos synchronization and communication in semiconductor lasers with optoelectronic feedback

In this paper, a bidirectional chaos communication system based on the optoelectronic feedback semiconductor lasers (SLs) is presented, and the synchronization characteristics and the communication performances of such system are simulated numerically. The results show that the high-quality synchronization with zero lag time and simultaneous bidirectional message transmission can be realized under the suitable system parameters; the internal parameter mismatches of the lasers have influence on the synchronization quality and communication performance, but this system still possesses good robustness to parameter mismatches. Meanwhile, the security can be ensured through a suitable encoding-decoding technique.     

Bidirectional chaos synchronization and communication based on mutually coupled semiconductor lasers with asymmetrical bias currents

In this paper, a bidirectional chaos secret communication system, based on mutually coupled semiconductor lasers (MCSLs) with asymmetrical bias currents, is proposed, and the synchronization characteristics and the communication performances of such a system are numerically investigated. The results show that the stable leader-laggard chaos synchronization can be achieved under relatively large asymmetrical bias current levels. Meantime, the influence of the intrinsic parameter variations of the laser on the synchronization quality is also considered, and the simulation reveals that this system still possesses good robustness to the parameter variations. Moreover, the influences of delay time and mutually coupling strength between the two lasers on chaos communication performance have also been discussed. Finally, unidirectional and bidirectional secret communication performances of such a system are examined under the chaos masking (CMS) encryption scheme, and the security of this system is also discussed.     

基于1550 nm垂直腔面发射激光器的长距离双向双信道光纤混沌保密通信研究

基于同一混沌信号光注入下两个1550 nm垂直腔面发射激光器 (VCSELs) 中两对应线性偏振模式之间的混沌同步, 提出了一种可实现信息的长距离双向双信道光纤混沌保密通信的系统模型, 并对该系统的同步、双向双信道通信以及光纤信道对信息传输的影响等性能进行了相关仿真研究. 结果表明: 在由驱动混沌激光器所产生的同一混沌光注入下, 两响应激光器中对应的两线偏振模式之间均可实现高质量的等时混沌同步, 且驱动激光器与两响应激光器间的同步系数较低; 基于两响应激光器之间对应线偏振模式的高质量混沌同步, 可实现双向双信道混沌通信; 采用单模保偏光纤 (或色散位移保偏光纤) 作为通信信道, 2.5 Gbit/s信息在传输60 km (或200 km) 后解调信息的Q因子能保持在6以上. 关键词： 垂直腔面发射激光器 (VCSELs) 双向双信道 混沌通信 光纤     

Two chaos synchronization schemes and public-channel message transmission in a mutually coupled semiconductor lasers system

Chaos synchronization and message transmission of a mutually coupled system consisting of two semiconductor lasers (SLs) and a partially transparent mirror (PTM) in between are investigated theoretically. Analytical results show that two types of chaos synchronization schemes, named as isochronal synchronization (IS) and leader/laggard synchronization (LLS), can be achieved by adjusting the reflectivity and position of PTM. By establishing SIMULINK model, numerical simulations illustrate that as the PTM is positioned at the center of two lasers, IS is available when the reflectivity of PTM is moderate. The LLS is achieved when the reflectivity of PTM equals to 0.5, which means feedback strength equals to coupling strength. Its lag time is just determined by the difference of feedback delay time. The investigations of mutual chaos pass filtering (MCPF) effects and the secure chaotic communication simulations indicate that IS allows real-time bidirectional message transmission on a public-channel, while LLS can achieve higher security chaotic communication by using its lag time as cryptography key. The demonstrated system can be used as a rudiment of array chaos communications system.     

Synchronization and control of chaos in coupled chaotic multimode Nd:YAG lasers

In this Letter we numerically investigate the dynamics of a system of two coupled chaotic multimode Nd:YAG lasers with two mode and three mode outputs. Unidirectional and bidirectional coupling schemes are adopted; intensity time series plots, phase space plots and synchronization plots are used for studying the dynamics. Quality of synchronization is measured using correlation index plots. It is found that for laser with two mode output bidirectional direct coupling scheme is found to be effective in achieving complete synchronization, control of chaos and amplification in output intensity. For laser with three mode output, bidirectional difference coupling scheme gives much better chaotic synchronization as compared to unidirectional difference coupling but at the cost of higher coupling strength. We also conclude that the coupling scheme and system properties play an important role in determining the type of synchronization exhibited by the system.     

基于双光反馈垂直腔面发射激光器的双信道混沌同步通信

利用双光反馈垂直腔面发射半导体激光器(VCSELs) 两个正交偏振模式输出的两个混沌信号作为混沌载波, 构建了一个双信道的混沌保密通信系统, 并对该系统的通信性能进行了数值仿真研究.研究结果表明: 通过合理的选取反馈参量, 双光反馈VCSELs两个偏振模式输出的混沌信号能很好地隐藏外腔反馈延时特性; 双光反馈VCSEL两个偏振模式输出的混沌信号通过偏振保持注入到接收VCSEL中, 在强注入锁定条件下可以实现很好的混沌同步, 同步性能对频率失谐的容忍性随着注入强度的增加而加强; 在附加混沌调制加密方式下, 500 Mbit/s的信号在传输过程中能够得到很好的隐藏, 同时在接收端可以成功解调; 随着通信速率的增加, Q因子呈现下降的趋势, 但对于 6 Gbit/s的信息, Q因子仍大于6. 关键词： 垂直腔面发射激光器 双光反馈 双信道 混沌通信     

Using polarization properties to enhance performance of chaos synchronization communication between vertical-cavity surface-emitting lasers

Enhanced chaos synchronization communication between vertical-cavity surface-emitting lasers (VCSELs) is investigated numerically, by adopting a polarization communication protocol where one polarization mode is used as the chaotic carrier and the orthogonal polarization mode is used as the disturbed signal. The chaos synchronization quality for the receiver laser (RL) and attacker laser (AL) are analyzed in terms of the cross-correlation coefficient. There are two distinct regions of good synchronization quality in the injection parameters space. In the first region, good synchronization quality can be ensured for both the RL and AL. In the second region, only the RL can realize chaos synchronization. We further discuss the security enhancement by comparing the communication performance between RL and AL for injection parameters within the second region. The results show that successful and robust decoding is only achievable for the RL.