Theoretical model of optical fiber secure communication system with chaotic multiple-quantum-well lasers

Chaotic synchronization of injected multiple-quantum-well lasers of optical fiber system and a theoretical model of optical fiber chaotic secure communication system are presented by coupling a chaotic multiple-quantum-well laser synchroniza- tion system and a fiber channel. A new chaotic encoding method of chaos phase shift keying On/Off is proposed for optical fiber secure communications. Chaotic synchronization is achieved numerically in long-haul fiber system at wavelength 1.55 μm. The effect of the nonlinear-phase of fiber is analyzed on chaotic signal and synchronization. A sinusoidal signal of 0.2 GHz frequency is simulated numerically with chaos masking in long-haul fiber analog communication at wavelength 1.55 μm while a digital signal of 0.5 Gbit/s bit rate is simulated numerically with c1haos masking and a rate of 0.05 Gbit/s are also simulated numerically with chaos shift keying and chaos phase shift keying On/Off in long-haul fiber digital communica- tions at wavelength 1.55 μm     

光纤混沌双向保密通信系统研究

本文提出光纤混沌双向保密通信设想,通过耦合光注入半导体激光器激光混沌全光耦合反馈同步系统和光纤传输信道,建立了光纤混沌双向通信系统模型,数值实现了该系统在长距离光纤传输中的同步,详细地分析了系统同步时间随光纤传输长度的关系.证明了光纤的交叉相位调制是限制激光混沌在光纤传输中同步的主要原因,导出了系统传输的非线性相移.数值模拟了具有正弦调制信号的调制频率0.5GHz混沌模拟通信和数字信号调制速率0.4Gbit/s以及20Gbit/s的混沌数字通信以及调制速率0.05Gbit/s 混沌键控通信的应用,计算出光纤混沌数字通信速率和同步误差等关系,还特别分析了系统解码特性和调制带宽,表明系统具有非常好的保密性能和具有高速率通信的能力.光纤混沌双向保密通信是可以实现的.     

双环掺铒光纤激光器混沌键控保密通信系统理论模型和数值模拟

提出双环掺铒光纤激光器激光混沌键控保密通信系统及理论模型,通过调制泵浦光参数以实现混沌键控保密通信;分析了通过参数调试补偿克服系统参数失配以减小同步误差的方法:模拟了两个单环掺铒光纤激光器激光和一个双环掺铒光纤激光器激光分别在0码和1码上的混沌同步及其解码,该系统在相空间,在时域和频域都具有很好的保密性能和反破译能力。     

半导体激光器混沌双向保密通信系统理论研究

提出外部光注入半导体激光器激光混沌全光耦合-反馈同步系统，进行激光器系统稳定性动力学分析并计算出最大Lyapunov指数，导出系统的同步误差扰动方程以及系统有混沌隐藏编码时的同步误差公式和解调公式，数值证明并模拟实现了系统的混沌同步，分析同步瞬态响应和噪声影响，该系统具有较强的抗干扰能力。模拟具有正弦调制信号的调制频率0．2GHz混沌模拟通信和数字信号调制速率0．2Gb／s的混沌数字通信以及调制速率0．05Gb／s混沌键控通信的应用，特别分析了系统解码特性和调制带宽，系统无论是在时域还是在频域，都具有非常好的保密性，该系统可以作为混沌双向保密通信使用。研究表明系统准许在一定范围内可以有参数失配，系统的实际应用是有可能的。     

非相干光反馈的半导体激光器混沌保密通信性能分析及其仿真

首先研究了非相干光反馈同步系统内部参数失配对系统同步性能的影响,并与相干光反馈的完全同步系统以及广义同步系统进行了比较,其次研究了非相干光反馈采用三种不同的信号调制解调方式(CSK,CMS,ACM),对三种不同频率(250 MHz,2.5GHz和12.5GHz)的信号进行了调制解调。通过MATLAB仿真实验可知,非相干光反馈混沌同步系统相对于相干光反馈完全同步系统更易于实现,同时保留了一定的对参数失配的敏感特性,从而确保了该系统比相干光反馈广义同步具有更高的安全性;在信号解调时,CSK只能解调出250MHz信号,CMS能解调出2.5GHz信号,ACM能够解调出高达12.5GHz的信号。     

ON/OFF phase shift keying for chaos-encrypted communication using external-cavity semiconductor lasers

Synchronization phenomena of two chaotically emitting semiconductor lasers subject to delayed optical feedback are investigated. The lasers are unidirectionally coupled via their optical fields. Our experimental and numerical studies demonstrate that the relative optical feedback phase is of decisive importance: a characteristic synchronization scenario evolves under variation of the relative optical-feedback phase mediating cyclically between chaos synchronization in conjunction with coherent fields, and uncorrelated states in conjunction with incoherent fields. As a key result, we propose, and numerically demonstrate, a novel ON/OFF phase shift keying method opening up new perspectives for applications in communication systems using chaotic carriers.     

Effects of message encoding and decoding on synchronized chaotic optical communications

Chaotic optical communication at 2.5 Gb/s is experimentally investigated using three major encoding and decoding schemes, namely chaos shift keying (CSK), chaos masking (CMS), and additive chaos modulation (ACM). The effects of message encoding and decoding on the chaotic dynamics, the chaos synchronization, and the chaotic communication performance are compared among the three schemes. In the schemes of CSK and ACM, it is found that a small amount of message injected into the chaotic dynamics can increase the complexity of the chaotic state dramatically. In the CMS scheme, the chaotic dynamics are found not to be influenced by the encoded message. The synchronization quality deteriorates dramatically with an increase in the message strength in CSK and CMS. The ACM scheme is found to have the best synchronization quality among the three schemes when there is an encoded message. Message recovery is demonstrated for each of the three schemes. The ACM scheme is found to have the best communication performance.     

Performance characterization of a closed-loop chaotic communication system including fiber transmission in dispersion shifted fibers

The transmission performance of an all-optical closed-loop chaotic communication system is numerically studied, assuming various span lengths of dispersion shifted fiber between transmitter and receiver. Calculation of the mean synchronization error and Q-factor values obtained from the corresponding eye diagrams has been carried out for two encoding methods (chaotic modulation and chaos shift keying) and two repetition rates (2.4 and 5 Gbps). It is shown that transmission impairments including chromatic dispersion, fiber nonlinearity, fiber losses, and amplified spontaneous emission noise of the inline amplifiers degrade significantly the synchronization quality especially when high-bit-rate message encoding is applied. The influence of key system parameters such as launched optical power, amplifier spacing, positive or negative dispersion, etc., to the transmission performance has been investigated. Acceptable system performance can be achieved for approximately 200 km at 2.4 Gbps.     

一种新型CD-QCSK混沌保密通信系统设计

针对现有混沌键控、混沌遮掩和混沌参数保密通信系统存在的一些缺点和实际应用的缺陷,提出了一种新型的混沌保密通信系统方案CD-QCSK系统的具体设计.同时对这个系统的实现原理进行了详细的推导,并基于Matlab/Simulink软件仿真实现了这个保密通信方案的信号传输,对其系统性能进行实验仿真分析,列举出了运用混沌加密前后效果图.该混沌键控系统同时兼具CDSK系统保密性高和QCSK误码率低的优点,系统的误码率性能和保密性也都有所提高,并且系统的传输速率是原有键控方式的4倍.     

Optical Chaotic Communication Using Generalized and Complete Synchronization

We propose a secure optical communication system based on the principles of generalized and complete chaotic synchronization. A transmitter and a receiver both composed by two chaotic external-cavity semiconductor lasers are coupled in a master-slave configuration to provide generalized synchronization, while the master lasers in the transmitter and in the receiver are completely synchronized through the synchronization channel via an optical fiber. A message is added to the transmitter slave laser and sent to the receiver through the information channel to be compared with the output of the receiver slave laser. The system is robust to a small mismatch of the laser parameters or of the coupling between the master and slave lasers, unavoidable in a real system, and can even enable a good communication up to a 5 Gb/s transmission rate using the chaos masking encryption method, when the master laseres are coupled bidirectionally.      

新型的CD-DCSK混沌键控保密通信系统

针对现有混沌键控通信系统存在的数据传输速率低性、安全性差等问题,提出一种新型的混沌键控通信系统——CD-DCSK(相关延迟—差分混沌键控),并对该系统的通信性能进行了深入地仿真分析.验证了改进的CD-DCSK同时兼具CDSK(相关延迟键控)保密性高和DCSK误码率低的优点,并且系统的数据传输速率更是提高到了原有键控方式的2倍.同时利用该新型的键控系统很好地实现了图像数据信号的保密传输,证明本系统在数字保密通信中的可实现性和高安全性.     

Synchronized chaotic optical communications at high bit rates

Basic issues regarding synchronized chaotic optical communications at high bit rates using semiconductor lasers are considered. Recent experimental results on broadband, high-frequency, phase-locked chaos synchronization, and message encoding-decoding at 2.5 Gb/s are presented. System performance at a bit rate of 10 Gb/s is numerically studied for the application of three encryption schemes, namely chaos shift keying, chaos masking, and additive chaos modulation, to three chaotic semiconductor laser systems, namely the optical injection system, the optical feedback system, and the optoelectronic feedback system. By causing synchronization error in the forms of synchronization deviation and desynchronization bursts, the channel noise and the laser noise both have significant effects on the system performance at high bit rates. Among the three laser systems, the optoelectronic feedback system has the best performance while the optical feedback system has the worst. Among the three encryption schemes, only the performance of additive chaos modulation with low-noise lasers is acceptable at high bit rates.     

基于耦合映象格子的混沌键控技术研究

提出一种基于耦合映象格子正反相同步的混沌键控方案,可利用系统提供的正反相同步信号提取出所传输信息,该方案有效地提高了信息的安全性。     

激光混沌外部调制包络隐藏及相位隐藏编码方法及其在光纤保密通信中的应用研究

该文研究光纤混沌包络隐藏与光纤相位隐藏保密通信理论模型,分析包络隐藏调制解调特性,导出解码公式;分析光纤自相位调制和光功率以及光放大器个数对系统的影响,提出接入相位控制器以减小非线性相移对同步解调负面影响的设想。数值模拟了调制速率0.2Gbit/s的混沌包络隐藏编码以及调制速率0.05Gbit/s的混沌相位隐藏编码及其在波长1.55m远程光纤数字保密通信中的应用,表明系统确具有较高的保密性能。     

光反馈垂直腔面发射半导体激光器的混沌驱动同步在保密通信中的应用

基于光反馈垂直腔面发射半导体激光器(VCSELs)混沌驱动同步,提出了一种光反馈VCSELs混沌保密通信系统。通过模拟信号和数字信号在该系统的混沌保密通信的实现,验证了该系统的可行性。进一步利用该方案实现了对文字和数字图像的保密通信,并对解密图像及原始图像灰度值的差值做了相关计算。数值模拟结果说明该通信方案具有良好的解密效果。     

基于改进的差分混沌键控（DCSK）保密系统

差分混沌键控(differential chaos shift keying,DCSK)利用了混沌信号类噪声的特性,采用非相干接收,避免了混沌同步问题。针对DCSK的保密性问题,提出一种改进的DCSK方案,通过仿真验证该方案的可行性,并对其性能进行深入分析。结论:改进的DCSK系统与传统的DCSK系统相比,误码率更低,保密性也更好。     

耦合半导体激光器的多调制延时混沌同步

为了研究多调制延时混沌系统的动力学,用数值计算法研究了非相干光反馈与非相干光注入半导体激光器的多常数延时与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与发送激光器频率完全匹配。另外,研究了非相干光反馈半导体激光器输出自相关函数。结果表明,多常数延时和多调制延时两种情况下都能获得高质量的同步,但在多调制延时系统中自相关函数的延时标识可以被隐藏,这一特性大大提高了系统的安全性,非常适用于混沌保密通信系统。     

Analysis and CMOS implementation of a chaos-based communication system

We describe the design and CMOS implementation of a baseband spread-spectrum communication system using chaotic signals for spreading digital data. The communication system uses a new chaotic modulation scheme called modified differential chaos shift keying (M-DCSK). The M-DCSK scheme and its characteristics are analyzed for single user and multi user applications. The chaotic signals were generated using a simple and robust circuit. The dynamics of this chaos generating circuit are also studied. The spectral properties of the system are investigated and compared with theoretical expectations.     

激光耦合同步及其在光纤混沌保密通信中的应用

本文建立了光纤混沌保密通信耦合同步系统模型,实现了外部光注入分布反馈半导体激光器激光混沌在长距离光纤传输中的耦合同步,证明了光纤的交叉相位调制是限制激光混沌在光纤传输中同步的主要原因,导出了这种传输的极限.该同步系统在长距离光纤混沌模拟和数字保密通信中的数值模拟表明,该系统确有较高的保密性能和反破译能力.光纤混沌保密通信是可以实现的.     

混沌系统的混合同步及其在安全通信中的应用

提出了一类混沌系统的混合同步方法。利用非线性系统的状态观测器，给出了一类混沌系统的同步和安全通信的简单有效的方法，并分析了系统的稳定性，对Rossler混沌系统的分析和仿真研究表明，该方法在混沌同步及安全通信中具有同步速度快、系统精度高等优良性能。