双区半导体激光器的超混沌及同步

基于双区半导体激光器的速率方程,研究了双区半导体激光器的超混沌现象,给出了双区半导体激光器产生超混沌的条件;利用驱动-响应法实现了双区半导体激光器的超混沌同步,通过计算激光系统最大条件李亚谱诺夫指数随注入强度的变化,得到实现超混沌同步的注入参量的取值范围.     

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.     

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。     

半导体激光器的混沌驱动同步

利用混沌驱动同步法研究了在电流调制下的半导体激光器的混沌同步。首先数值计算了系统最大Lyapunov指数随调制强度的变化情况,确定了激光器处于混沌态的参数区间。然后分别实现了同地激光器系统和异地激光器系统的混沌驱动同步。响应激光器间相关系数的数值计算表明,两种激光器系统均能达到很好的混沌同步。以三个响应激光器为例,将响应系统推广到多个激光器,并且实现了两种激光器系统的混沌同步。     

偏振选择互注入半导体激光器的混沌同步

研究了偏振选择互注入条件下半导体激光器的同步和混沌滤波效应。将单模互注入速率方程扩展为包含两个偏振态的理论模型,并选择X偏振态作为互注入形式,不仅为激光器产生混沌和实现同步提供了条件,还可以完全抑制Y偏振光,实现了纯偏振模式同步。通过频率失调的引入,保持了激光器主从地位的稳定。研究结果表明,主从激光器实现了时差等于注入延时的混沌同步,输出功率表现出高频振荡并伴随有对称性破坏现象。对主激光器进行调制时,同步系统表现出与单向注入相似的混沌滤波效应;对从激光器进行调制时,系统的混沌滤波效应并不明显。     

单向耦合半导体激光器之间的混沌同步研究

研究了单向耦合半导体激光器之间的混沌同步。通过计算两个单向耦合的半导体激光器模型的Lyapunov指数,确定了耦合强度的取值范围。进一步设计了耦合控制器,使响应系统的状态变量精确同步于驱动系统。仿真模拟结果表明,该方法可快速有效地实现半导体激光器的混沌同步。     

激光混沌耦合同步及其在保密通信中的应用

建立了外部光注入半导体激光器激光混沌耦合同步系统，导出了耦合条件下的激光扰动方程和激光同步扰动方程。成功模拟了外部光注入波长1．3lμm分布反馈半导体激光器的激光混沌耦合同步，其同步误差小且抗噪声干扰能力强。该同步系统在混沌模拟和数字保密通信中的数值模拟表明，无论是在时域还是在频域，信息都难以被分离，该系统确有较高的保密性能和反破译能力。     

保密通信以及加密措施与设备

0307660基于混沌无振荡同步的保密系统[刊]/胡国杰//计算机工程.—2002,28(11).—149～150,182(E)0307661激光耦合同步及其在光纤混沌保密通信中的应用[刊]/颜森林//电子学报.—2002,30(11).—1663～1667(C)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     

单向耦合VCSEL偏振模的同步与编码

为了研究单向耦合垂直腔面发射激光器系统的混沌动力学及其在通信中的应用,采用数值仿真的方法,理论研究了两个单向耦合的垂直腔面发射激光器偏振模的同步特性,并通过对发射激光器偏振态相位的调制实现了该系统的编码。结果表明,主激光器和从激光器相应模式间可以获得高性能的同步,而且存在两个明显的同步区域——完全同步和注入锁定同步。加载的数字信息也可以在从激光器每个偏振分量中还原,这表明可以利用单模或多横模垂直腔面发射激光器进行多信道混沌通信。     

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.     

An integrated equivalent circuit model for relative intensity noise and frequency noise spectrum of a multimode semiconductor laser

Relative intensity noise (RIN) and the frequency/phase noise spectrum (FNS) equivalent circuit of a multimode semiconductor laser diode are derived from multimode rate equations with the inclusion of noise Langevin sources. FNS is an important parameter in optical communication systems, and its circuit model is presented, for the first time, in this paper. Both circuit models for RIN and FNS are integrated in one circuit. RIN and FNS are calculated as functions of frequency, output power, and mode number. It is shown that the RIN of the main mode is increased in the multimode lasers with higher mode numbers. Furthermore, we show that RIN and FNS are enhanced for higher output power. The dependency of a multimode laser diode linewidth on output power is also analyzed using the model.     

External cavity controlled operation of a semiconductor diode gain element in series with an optical fiber

The series combination of a semiconductor diode gain element (a diode laser whose end facets have been antireflection coated) and an optical fiber has been placed inside an external cavity and the combined system has lased in a single spectral line whose width was less than the1.7 times 10^{-5}-nm (7.5-MHz) resolution of the scanning Fabry-Perot interferometer used in the measurement. This result has been achieved with either a single-mode or a multimode optical fiber in series with the diode gain element and for experiments in which a polarizer, oriented so its polarization is parallel to the diode gain element polarization, was placed at the other end of either fiber. The output of the external cavity is temporally stable as measured both by a 225-MHz-bandwidth detector system and a spectrum analyzer. Over a one minute interval the maximum fluctuation in the output frequency of the external cavity was found to be 2 MHz. Analysis of the threshold behavior of the external cavity for the cases where the multimode or single-mode fiber are in the cavity indicates that the coupling coefficients for either fiber are nearly the same. Without an external cavity, the coupling coefficient from the diode gain element (or from a similar, not anti-reflection-coated, laser) to the multimode fiber is over five times larger than that to the single-mode fiber. These coupling results are explained by postulating that for the multimode fiber, only one or a selected number of the many modes of the fiber can participate in the laser action of the external cavity. It is believed that only these mode(s) are reflected back into the fiber by the spherical mirror in appropriate phase and angle to participate in the laser emission.     

60GHz毫米波ROF系统的光源研究

提出了把通过注入锁定方法得到的FP单模输出光源应用到60GHz毫米波ROF系统中的方法.通过利用窄带放大自发辐射(ASE)光源插入FP半导体激光器以实现波长锁定,改变FP激光器的多模输出,得到单模输出的廉价光源的方法,成功地为ROF系统的基站提供了激光器.     

A high-power tapered and cascaded active multimode interferometer semiconductor laser diode

A high power semiconductor laser diode with a tapered and cascaded active multimode interferometer (MMI) cavity was designed and demonstrated.An output power as high as 32 mW was obtained for the novel laser diode with a tapered and cascaded active MMI cavity,being much higher than the 9.8 mW output power of the conventional single ridge F-P laser with the same material structure and the same device length due to the larger active area;and also being higher than the 21.2 mW output power of the rectangular and cascaded active MMI laser diode with nearly the same structure,except for the shape of the MMI area.In addition,the tapered and cascaded active multimode interferometer laser showed stable single mode outputs up to the maximum output power.     

Performance characterization of high-bit-rate optical chaotic communication systems in a back-to-back configuration

A comparative study of three data-encoding techniques in optical chaotic communication systems is reported. The chaotic carrier is generated by a semiconductor laser subjected to optical feedback and the data are encoded on it by chaotic modulation (CM), chaotic masking (CMS), or chaotic shift keying (CSK) methods. In all cases, the receiver-which is directly connected to the transmitter-consists of a semiconductor laser similar to that of the transmitter subjected to the same optical feedback. The performance of this back to back configuration is numerically tested by calculating the Q-factor of the eye diagram of the received data for different bit rates from 1 to 20 Gb/s. The CM scheme appears to have the best performance relative to the CMS and CSK scheme, before and after filtering the residual high-frequency oscillations remaining due to nonperfect synchronization between the transmitter and receiver. Moreover, in all encoding methods, a decrease in the Q-factor is observed when the repetition bit-rate of the encoding message increases. In order to achieve as high Q-factor values as possible, a well-synchronized chaotic master-slave system is required.     

光子集成混沌半导体激光器研究进展（特邀）

混沌激光具有宽频谱、类噪声、低相干等特性,在保密光通信、高速随机数、混沌激光雷达、混沌光时域反射仪和分布式光纤传感等领域具有重要的应用价值。光子集成混沌激光器是混沌激光应用的核心器件,具有体积小、性能稳定、成本低等优点。综述了近十年来光子集成混沌半导体激光器的进展及其主要应用。首先介绍了混沌半导体激光器的集成方式;接着介绍了光子集成混沌半导体激光器的分类,根据其扰动方式讨论了直腔单反馈、多腔反馈、环形腔反馈、二维外腔反馈、互注入等结构,并对比分析了各自的优势与输出特性;然后介绍了光子集成混沌半导体激光器在光时域反射仪、保密光通信和高速随机数产生等方面的应用;最后,讨论了光子集成混沌激光器的关键集成技术、时延特征抑制及间歇混沌的特性。     

半导体激光器自动控制系统设计

根据半导体激光二极管的工作原理 ,设计了一种利用单片机实现半导体激光器功率稳定输出的自动控制系统。该系统包括恒流源、光功率反馈、保护电路、温度控制等部分。系统具有激光功率值的实时控制、显示和设置 ;工作温度值的实时控制、显示和设置 ;系统软开关和软保护等功能。     

半导体激光器混沌方式研究

激光混沌保密通信是近年来新兴的一个领域,它通常利用半导体激光器产生混沌,再将传输信号隐藏于混沌信号中,从而达到保密通信的目的。由于每个学者方式取向不同从而衍生出多种产生混沌的方式,本文参考大量文献,综合各种常用方式,将产生混沌的方式进行系统分类。首先分为反馈混沌和注入混沌;其中把反馈型混沌按反馈物质的不同又分为光反馈混沌和光电反馈混沌,而光反馈又有两种类型:反馈相干光和反馈非相干光,最近,更有学者在此基础上提出了双光反馈;然后分别阐述各种混沌类型的系统模型、理论模型及优缺点,将这个新兴领域的理论系统化、完整化。     

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.      

Demultiplexing chaos from multimode semiconductor lasers

We show numerically that the injection of two chaotic modes of a multimode semiconductor laser with optical feedback into two single-mode stand-alone semiconductor lasers leads to chaotic synchronization between the respective intensities. The effect of parameter mismatch between the transmitter and receiver lasers is examined, and it is concluded that the observed synchronization is a consequence of injection locking. Under these conditions, the possibility of using this demultiplexing scheme for message transmission is examined.