GHz Bandwidth Message Transmission Using Chaotic Vertical-Cavity Surface-Emitting Lasers

Chaotic message encoding and decoding in unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs) with polarization-preserved and polarization-selected optical injection has been studied experimentally. A GHz message has been successfully encoded in the chaotic transmitter and decoded from the receiver with polarization-preserved optical injection. In contrast decoding using polarization-selected optical injection was achieved at only 330 MHz. It has also been demonstrated that GHz message extraction can be achieved using both normal and inverse chaos synchronization thus providing an opportunity for exploiting polarization properties of VCSELs for duplexed chaotic message transmission.     

两台非全同激光器的混沌同步

对空间上相互耦合的两台非全同固体激光器的动力学行为进行了分析。当两台激光器的抽运受到调制而每台激光器的损失不同时 ,两台激光器输出的强度会出现周期性运动、混沌同步和失去同步的情况。激光中混沌同步的发生 ,同两台激光器之间的耦合程度有关。当耦合较强时发生周期性运动 ,耦合适中时处于混沌状态 ,在特定条件下产生混沌同步 ,而耦合较小时 ,两台激光器的振荡就相对独立。     

Experimental Observation of Chaotic Dynamics in Two Coupled Diode Lasers Through Lateral Mode Locking

The nonlinear and chaotic phenomena in lateral coupled diode lasers have been widely studied theoretically. In this work an experimental analysis of the complex nonlinear and chaotic dynamic regimes experimentally observed in these devices and the mechanisms that produces it is made. This analysis is set by means of the RIN electrical spectrum and of the high resolution Fabry–Perot optical spectrum. A mapping of the nonlinear occurrences in these devices is obtained and a study of the relation between the relaxation oscillation frequency and the lateral locking frequency is achieved.      

多变量耦合实现双环掺铒光纤激光器混沌同步

根据双环掺铒光纤激光器的理论模型,提出多变量单向耦合法实现混沌同步,对主从系统模型进行数学推导,研究不同参数条件下双环掺铒光纤激光器的混沌同步,得到实现混沌同步的条件,并在Simulink平台下动态仿真。结果表明,衰减系数不同的两个双环掺铒光纤激光器,主激光器通过定向耦合器驱动从激光器,主从系统可以实现精确混沌同步,且随着反馈强度的增大,实现系统混沌同步的时间越短,反馈强度的取值范围由衰减系数和耦合系数确定;选取不同的系统初值,主从系统可实现混沌同步,系统初值对达到混沌同步时间的影响可忽略不计;在主从系统中引入随机高斯噪声,主从系统仍可实现较好的混沌同步。     

Message Encryption by Phase Modulation of a Chaotic Optical Carrier

We present a numerical and experimental evaluation of message encryption by phase modulation, using a chaotic optical carrier generated by a laser subject to delayed optical feedback. This method offers better security than the conventional amplitude masking, where the signal is simply added to the chaotic waveform     

Characteristics of Fast Physical Random Bit Generation Using Chaotic Semiconductor Lasers

We investigate the characteristics of fast random bit generation using chaotic semiconductor lasers. The optical amplitudes of two lasers with chaotic oscillations induced by optical feedback are each sampled at a fixed rate to extract binary bit sequences which are then combined by an exclusive-OR operation to obtain a single random bit sequence. Bit sequences generated at rate of 1 Giga bit per second are verified to pass statistical tests of randomness. We describe the dependence of randomness on laser parameters, in particular the injection current, the external cavity length and the feedback strength. The results provide clear empirical guidelines for tuning the chaotic laser parameters to achieve random bit sequences. This study shows that chaotic laser devices can be fast and reliable sources of physical entropy for computing and communication applications.      

Characterization of Quantum-Cascade Lasers Using Single-Pass Transmission Spectroscopy

The study of the electron distribution and intersubband transitions in quantum cascade (QC) lasers provides fundamental insights into the laser operation. Measurements on intersubband transitions are often performed on QC lasers under nonoperating conditions, i.e., at zero electric field. In this study, a single-pass transmission technique that allows for probing of QC lasers under operating conditions was used. The measurements and analysis were done on QC lasers with vertical and diagonal transition active region designs operating at $lambdasim 10 mu{hbox {m}}$. The single-pass modal gain coefficients, extracted for the vertical transition design, were 24.04 cm/kA at 100 K, 21.36 cm/kA at 125 K, 14.25 cm/kA at 150 K, and 5.26 cm/kA at 175 K.      

A Theoretical Analysis on Transmission Characteristics of Semiconductor Lasers

In this paper, on the basis of classical control theory transmission characteristics of semiconductor lasers will be analyzed. In the case of small-signals semiconductor lasers is considered as an isolated linear system and the rate equation describing its physical process is linearized; four kinds of transmission functions showing its transmission characteristics have been obtained by using network theory; response characteristics to optical-electrical input signals and corresponding equivalent network are then given according to the transmission functions, and transmission characteristics are, in turn, analyzed and synthesized according to the transmission functions and the equivalent network.     

Parameters Estimation of Chaotic Telemetry System between Two Different Time-delayed Chaotic Systems

针对混沌遥测系统的参数估计问题,研究了基于混沌同步的不同混沌时延系统的 参数估计方法。构造了利用不同混沌系统进行参数估计的自适应方案,利用Krasovskii -Lyapunov理论推导出两个不同混沌时延系统同步和参数估计的充分条件。所提方案应用到 混沌遥测系统参数估计可以有效估计系统参数。非合作者可用所构造方法利用不同混沌 系统获取混沌遥测系统的有用信息。仿真分析验证了方案的有效性。     

微腔激光器数码调制及其光纤传输的研究

从微腔半导体激光器速率方程出发，分析讨论了微腔激光器的脉码调制特性，发现微腔具有较规则的脉冲响应，可以减少误码率；自发发射因子为０．１的微腔，具有脉码率高达５０Ｇｂｉｔ／ｓ良好的调制眼图，微腔激光器在光互联中将有广泛的应用前景。模拟了以微腔激光器为光源的光纤通信系统，给出脉码率为１０Ｇｂｉｔ／ｓ传输不同距离的接收眼图，证明能够实现６０ｋｍ的传输。     

光反馈垂直腔面发射半导体激光器的混沌驱动同步

基于光反馈垂直腔面发射半导体激光器动力学模型,通过分析光子数密度随光反馈强度变化的分岔情况,确定了激光器处于混沌态时的参数区间。利用混沌信号驱动同步方案,实现了两个被驱动激光器的精确混沌同步,并通过对两个被驱动激光器相关系数的分析,确定了它们达到精确混沌同步的参数区间。研究了参数失配对同步的影响,结果表明该同步方案有很好的稳健性。     

移动通信网中GPS定位信息传输

介绍了基于GSM和GPRS的GPS定位信息传输系统,通过各系统工作过程的研究对其性能进行了分析.展望了未来移动通信发展对GPS定位信息传输的深远影响.     

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.     

两路纳秒脉冲光纤激光相干合成的实验研究

报道了两路纳秒脉冲光纤激光的相干合成(CBC)实验。利用主振荡功率放大(MOPA)结构搭建两路全保偏光纤激光放大器,利用随机并行梯度下降(SPGD)算法对两路放大器进行相干合成,获得了重复频率10MHz、脉冲宽度10ns、平均功率50mW的脉冲激光输出。系统闭环时目标圆孔内能量提高了1.76倍,远场光斑条纹对比度提高了4.38倍。     

提高混沌同步通信系统传输效率的方法

本文讨论了混沌同步数字通信系统的传 输效率,考察了驱动信号取样周期对同步性能的影响,适当选取取样周期,可减少驱动信号的数据量。由于传输效率与系统设计有关,本文提出一种利用时空混沌同步的加密通信方案,该方案将时空混沌信号用作加密密钥,每个驱动信号样本可使时空系统同时产生多个密钥, 对多个消息数据进行加密,从而有效地提高了数据传输效率,为实现语音信号在计算机网上的加密实时传输提供了一条新的途径。     

SDH光传输设备在专用网中的应用

扩充了接入功能的SDH设备是为了适应广大本地传输网、移动、电力专网等的特殊需求（如上下业务较少，而要求接口种类丰富），在标准SDH设备的基础上，集成了独特的交叉连接功能和丰富的业务接口种类具有极强的环境适应能力，小巧的结构，为许多领域中的专网提供了性能价格比较高的传输接入网络解决方案。     

非相干解调JTIDS系统报文传输性能分析

联合战术信息分发系统(Joint Tactical Information Distribution System,JTIDS)是美军C4ISR系统的核心组成部分。目前针对其链路性能建模多基于相干解调方式,而JTIDS采用非相干解调方式。因此,在对JTIDS多层调制技术进行分析建模基础上,研究了2种非相干解调方式JTIDS接收模型,导出了这2种接收模型下JTIDS系统在加性高斯白噪声信道下的符号错误概率表达式,通过对比分析各模型下的数值结果表明,非相干接收软判决译码模型是JTIDS性能分析的适合模型。为后续建立JTIDS仿真平台、评估JTIDS通信网络性能提供了理论依据。     

两次MOVPE生长的大功率InGaAs－GaAs－InGaP掩埋异质结应变量子阱激光器

本文给出了带有Ｉｎ０．４９Ｇａ０．５１ｉ包层的ＩｎＧａＡｓ－ＧａＡｓ应变量子阱激光器实验结果。镀有ＡＲ－ＨＲ膜、并有ｐ－ｎＩｎＧａＰ电流阻挡结的掩埋异质结激光器，在连续波（ＣＷ）和室温（ＲＴ）下，给出３．１ｍＡ的低阈值电流和９５ｍＷ的高功率输出。这是首次以两次ＭＯＶＰＥ方法生长制作的ＩｎＧａＡｓ－ＧａＡｓ－ＩｎＧａＰ掩埋异质结激光器。     

入侵检测代理消息机制的研究

在网络中系统之间消息的交换十分重要.文中研究了在入侵检测代理之间消息传输的相关机制,采用层次编码方式对消息类编码,在消息传输时使用消息的编码和相应的参数,确保语义的惟一性.     

JTIDS数据链报文传输可靠性分析及仿真

联合战术信息分发系统[1](Joint Tactical Information Distribution System,简称JTODS)采用组合调制体制以及多层编码体系保证报文传输的可靠性,本文提出了JTIDS数据链报文传输可靠性的评价模型,分析了该系统在莱斯衰落信道环境和部分频带干扰条件下的符号误码率和报文丢失率,并利用SIMULINK仿真平台对JTIDS数据链报文传输过程进行设计、建模和仿真,并对结果进行分析.仿真结果显示,由于JTIDS系统将RS编码、交织等多种编码技术和DS/FFH MSK调制技术相结合,使其在复杂信道环境下保持较低的符号误码率及报文丢失率,满足数据链报文传输可靠性的要求.