Chaos synchronization and communication of mutual coupling lasers ring based on incoherent injection

A chaos secure communication system of mutual coupling lasers ring based on incoherent optical injection is proposed, in which fine tuning of optical frequency is not required compared with other schemes based on coherent optical injection. Therefore the secure communication scheme is attractive for experimental investigation. The dynamics of semiconductor lasers in the coupling ring are examined. Numerical investigations indicate that zero lag synchronization can be achieved under equal coupling time and strength of mutual coupling. Furthermore, by chaos shift keying (CSK), secure communication is simulated with a random bit stream of 1.0 Gbit/s. The results confirm the possibility of applying incoherent schemes of mutual coupling lasers ring to realize chaotic secure communication.     

无线光通信系统中的光接收机设计

介绍了无线光通信的特点，比较了光电检测器、光纤接收模块、自聚焦透镜和多模光纤接收机耦合三种设计方案，提出了自聚焦透镜和多模光纤之间的耦合设计是最优方案。详细讨论了自聚焦透镜和多模光纤之间的耦合设计和电信号处理过程。试验证明，采用该方案后系统输出信号的信噪比显著提高，完全可以满足通信系统的要求。     

Beam reception and data transmission performance analysis of optical taper used in a mobile wireless optical communication

Mobile wireless optical communication system was demonstrated experimentally by using a special solid coupling optical taper. The performance of special solid coupling optical taper and the data transmission performance with 240 Mbit/s were investigated on the rectilinear orbit between the mobile terminal and the fixed terminal. The experimental results shown that the scheme used in the mobile wireless optical communication system is reliable and quite simple, which could be widely used in future.     

某型通信电台超宽带辐照效应

为了研究通信装备受超宽带电磁脉冲干扰的影响规律,对某型通信电台开展了超宽带电磁脉冲辐照效应实验。研究发现:在场强为50 kV/m,脉冲下降沿小于1 ns、脉宽小于2 ns的超宽带辐射场下,受试电台出现显示屏显示异常,造成该效应的电磁能量耦合通道为电台显示面板;增大超宽带辐射场至150 kV/m时,短波电台出现显示屏显示异常、死机、重启、声音中断（调谐后恢复）等效应;超宽带脉冲对通信电台的效应只与辐射场强度有关,不存在累积,造成这些效应的电磁能量耦合通道为电台显示面板和供电电源线。     

Bidirectional communication using delay coupled chaotic directly modulated semiconductor lasers

Chaotic synchronization of two directly modulated semiconductor lasers with negative delayed optoelectronic feedback is investigated and this scheme is found to be useful for efficient bidirectional communication between the lasers. A symmetric bidirectional coupling is identified as a suitable method for isochronal synchronization of such lasers. The optimum values of coupling and feedback strength that can provide maximum quality of synchronization are identified. This method is successfully employed for encoding/decoding both analog and digital messages. The importance of a symmetric coupling is demonstrated by studying the variation of decoding efficiency with respect to asymmetric coupling.     

Shannon information capacity of time reversal wideband multiple-input multiple-output system based on correlated statistical channels

Utilizing channel reciprocity, time reversal(TR) technique increases the signal-to-noise ratio(SNR) at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output(MIMO) communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems.     

基于时域有限差分法分析等离子波导和介质波导耦合

使用Rsoft软件中的时域有限差分模块Fullwave分析二维介质波导和等离子波导耦合特性,利用软件仿真耦合结构并自动计算出光在介质波导和等离子波导中传输的耦合效率,进而测绘耦合效率随波导尺寸和光波长的变化曲线图,发现MDM导波结构的缝隙宽度和光通信质量密切相关,在确定尺寸下,传输损耗随传输距离成指数衰减.根据分析得到的耦合效率变化规律发现介质波导和等离子波导间距最佳点都应设为15 nm,进而优化波导的几何结构参数后,可以将耦合效率提高到83%.     

利用时空混沌同步进行数字加密通信

提出一种利用时空混沌同步的计算机网络数字加密通信方案,并用软件实现了语音双工实时密码通信.在该方案中,收、发端两个单向耦合映射格点(OCOML)系统被同一混沌信号所驱动而达到同步,其时空混沌输出信号分别用作加密和解密的密钥序列,OCOML的耦合参数为系统的主密钥.系统的主要优点是传输效率高,便于用软件实现实时通信,且通信的安全性获得了改善. 关键词： 时空混沌同步 密码系统 传输效率     

Sprott-B和Sprott-C系统之间的耦合混沌同步

Sprott-B和 Sprott-C是拓扑等价的异结构混沌系统. 利用系统变量线性耦合方法实现二系统之间的混沌同步；根据Lyapunov稳定性理论，确定了二系统达到同步时耦合系数的阈值. 设计了实现二系统耦合同步的实验电路，实验结果证明了理论分析的正确性. 基于Sprott-B和 Sprott-C异结构系统混沌同步，提出了一种新的具有更好保密性能的混沌保密通讯方法. 关键词： 线性耦合 混沌同步 异结构系统 拓扑等价     

单模与多模光纤耦合器的光束合波

现有的光纤耦合器在作为分波器使用时具有较低的插入损耗,在作为合波器时插入损耗较大,为实现低损耗合波目的,提出一种由单模与多模光纤共同构成的混合型光纤耦合器。利用耦合波方程理论分析其工作原理,计算机模拟其耦合过程。采用熔锥法制作工艺,完成单模与多模光纤耦合器的制作,实验结果与理论模拟相吻合;该器件单模到多模光纤的耦合效率、多模到多模光纤的耦合效率均在90％以上,实现了两路光束的功率合波。作为低插入损耗合波器件可广泛应用于光通信以及双包层光纤激光器抽运光的注入。     

大发光面脉冲半导体激光器与多模光纤的高效耦合

给出一种实现大发光面脉冲半导体激光器与标准通信光纤的高效耦合方案，实测耦合效率达２１％。     

双芯高双折射光子晶体光纤耦合特性研究

设计了一种双芯高双折射光子晶体光纤,采用多极法（multipole method）和光纤的模式耦合理论研究了光纤的双折射、耦合长度以及色散特性.数值研究发现,对于空气孔节距 Λ=1.2　μm,空气孔直径d=1.0　μm的光纤,在1.55　μm处双折射度为1.24×10^-2;对应x偏振模的耦合长度为21.6　μm,对应y偏振模的耦合长度为24.3　μm. 这种具有高保偏度和极短耦合长度的双芯光子晶体光纤对于微型光子器件的研制具有重 关键词： 光子晶体光纤 双芯 双折射 耦合长度     

高功率微波作用下光电转换器的抗干扰特性分析

随着智能电网上升成为国家战略,其高速、高集成度的光纤通信网络通信的安全性和可靠性成为了一个需要重点关注的问题,然而电网中广泛使用的光电信号转换装置却并没有针对可能遭受到的强电磁脉冲攻击进行防护,一旦被干扰或损伤,可能危及整个通信网络乃至电网的安全性。针对一种常用的光电转换器,开展了典型高功率微波环境下的辐照效应试验,发现其在较低场强即可能出现干扰和扰乱的效应现象。并通过进一步的壳体耦合仿真分析和典型半导体器件的干扰机理研究,明确了散热孔阵为主要的能量耦合通道,低频(L波段)耦合效果优于高频(S波段)近一个量级。耦合场通过场路耦合主要作用于转换芯片,本质原因可能是半导体器件的闩锁效应。     

盲优化波前校正提高自由空间光通信光纤耦合效率

为了提高自由空间光通信系统的光纤耦合效率,介绍了一种新颖的基于盲优化波前校正的自适应光学系统。该系统不使用波前传感器,而是在信号进入接收端前,将畸变光信号分束后送入光电探测器,进行耦合效率计算;采用耦合效率的估计公式斯特列尔比为目标函数,用随机并行梯度优化算法最大化目标函数,以实时控制变形镜,从而使耦合进入单模光纤的光达到最优。数值结果表明,此系统能使光纤耦合效率从6%提高到约60%。     

全光纤声光调制器的耦合模理论研究

利用适于普通通信光纤的耦合模方程,从理论上分析了一种全光纤声光调制器.并从理论上研究了基于普通通信光纤的全光纤声光调制器,得到了这种全光纤调制器的输出结果.     

Intensity coupling and synchronization of chaotic lasers

The synchronization of chaotic lasers was studied considering the coupling scheme with the intensity of light pulses from one laser saturating the other one. The experimental synchronization of two single mode CO2 lasers with saturable absorber is reviewed. Numerical simulations are presented for diode lasers made chaotic by optical feedback. Optical intensity saturation coupling was introduced in Lang-Kobayashi equations. Parameters were chosen such that both lasers were uncorrelated and chaotic before coupling and partially synchronize after coupling. Correlation functions for the numerical solutions were used to characterize the properties of the synchronism. They show partial in-phase and antiphase synchronism for the pulse intensities, depending on the coupling mechanism. These synchronisms are independent of optical interferometric effects and so, relevant for communication applications.     

西安理工大学无线光通信系统自适应光学技术研究进展

总结了国内外自适应光学技术在无线光通信系统应用中的研究进展和技术分类,同时介绍了西安理工大学在该领域的工作,包括有波前测量的自适应光学系统、无波前测量的自适应光学系统、液晶空间光调制器波前校正、偏摆镜和变形镜组合的波前校正、空间光光纤耦合自适应光学波前校正等。自适应光学技术可有效修正无线光通信系统中由大气湍流引起的畸变波前,提高耦合效率和通信性能。虽然这些方法在理论分析和工程实际中尚不完善,但不失为人们在该领域进行的有益探索。     

自均衡线性相位高温超导滤波器的设计

针对第三代移动通信CDMA 2000标准用超导滤波器的技术要求,设计了一种自均衡线性相位高温超导滤波器,给出了14阶三个交叉耦合的CQ结构滤波器理论计算结果、等效电路、耦合矩阵,设计的滤波器中心频率为830MHz,65%带宽内的群时延波动优于±10ns,滤波器模拟仿真结果与理论计算很好得吻合。     

CMOS compatible highly efficient grating couplers with a stair-step blaze profile

A novel grating coupler with a stair-step blaze profile is proposed.The coupler is a CMOS process compatible device and can be used for light coupling in optical communication.The blaze profile can be optimized to obtain a high efficiency of 66.7% for the out-of-plane coupling at the centre wavelength of 1595 nm with a 1 dB bandwidth of 41 nm.Five key parameters of the stair-step blaze grating and their effects on the coupling are discussed for the application in L band telecommunication.     

Wavelength-division-multiplexing system with photonic crystal self-collimation and co-directional coupling effect

A wavelength-division-multiplexing system with high compactness and extremely simple structures is designed and analyzed theoretically for optical communication wavelengths. The structure consists of a self-collimation region, a coupler, a coupling section, and two arbitrarily bent periodic dielectric waveguides (PDWGs). Operation principle of the devices is based on self-collimation and directional coupling mechanism. The equal-frequency contours (EFCs) are nearly flat from 0.17–0.22 (2πc/a), thus the self-collimation region acts as a multiplexer. Operation principle of the demultiplexer is based on directional coupling in two parallel periodic dielectric waveguides. The device performances have been evaluated by the finite-difference time-domain simulations coupled with perfectly matched layer (PML) boundary conditions.