波分复用技术在光纤通信系统中的应用

一根光纤可传输很大的通信信息量,可同时给若干用户传输视频信号、电话信号以及数据和控制信号等,这样,就会降低传输系统的造价。要实现这种传输技术,就得有效地将若干用户的信号组合到一根公共光纤上去再进行传输。而在另一端,再把这些经过组合的信号分开,以便传输给指定的用户,这就是所谓的波分复用技术(WDM)。贝尔北方研究所的新技术实验室已应用这种技术建立了模型系统。采用这种技术可以更经济地把综合服务(话音、数据和视频)引进用户家中。信号在光纤中的传输图1.a示出的是光纤传输信号的基本方法。某一单个光源发射出一特定波长的光,经     

多通道水声同步光纤采集存储系统设计

介绍了一种水声信号采集存储系统,该采集存储系统水下将8路水声模拟信号进行同步A／D采样,然后复用成1路高速数字信号,通过一根光纤远距离传输到岸上的上位机,上位机可以实现数据的实时存储和波形显示功能。该水声同步采集系统通过光纤作为传输介质,传输距离远,抗干扰能力强;可用于港口、海上钻井平台和石油码头等设施的安全防范及信息采集。     

分布式宽带微波光纤传输幅相一致性技术

针对分布式宽带微波频率信号光纤传输的幅相一致性,本文设计了一种反馈控制方案.由于无法通过待传输宽带微波信号直接获取光纤传输时延信息,引入了一个点频参考信号.由于参考信号和待传输宽带微波信号在同一根光纤中波分复用传输,参考信号可以感知和反馈光纤传输时延及其波动.为了满足多路信号接收的幅相一致性,设计了基于光开关的轮询式多...     

波分多路复用-纤维光学系统的新应用

一根光纤可传输很大的通信信息量——给几个用户提供电视信号加上各户的电话,还有外加的传输数据和控制信号的容量。如果一根光纤能为不止一个用户服务,传输系统的造价就会降低。因此,需要一种有效的方法来将若干用户的信号组合到一根公共光纤上去再进行传输,然后在另一端把这些经组合的信号分开,以便输送。贝尔——北方研究所的先进技术实验室已经建立了一个用来演示如何实现这种传输的模型系统。所选用的方法采用最新的波分复用技术,即利用光信号的不同波长来组合和分离光信号的方法。     

全光网络的演进和发展

光通信采用的光复用技术主要有两种：时分复用（ＴＤＭ）和波分复用（ＷＤＭ）技术。对于ＴＤＭ来说，使用单一波长的光信号，光纤带宽易于控制；但缺点是传输容量要进一步增加时，必须把光脉冲压缩得更窄，就需有更高速和精密的光器件去保证。对于ＷＤＭ来说，各信道的速率相对较低，不必设置精密的定时电路。一根光纤如只传输一路光信号，只限于４０Ｇｂｉｔ／ｓ，而ＷＤＭ是让一根光纤同时传输几路或几十路不同波长的光信号，就可达到Ｔｂｉｔ／ｓ级的信号传输。 ＤＷＤＭ网络已得到了广泛的应用。它满足了提升通信容量的需要，但它本身…     

双向混合信号光纤传输系统的设计与实现

介绍了一种新的多路信号光纤数字化传输方法,基于FPGA设计了混合信号光纤传输系统,并通过实验验证了系统的准确性.该系统不仅能传输模拟信号还能传输数字信号,不仅能传输低速数字信号还能传输高速脉冲信号,此外还能实现双向CAN通信.     

名词解释

名词解释（续上期）２２波分复用（ＷａｖｅｌｅｎｇｔｈＤｉｖｉｓｉｏｎＭｕｌｔｉｐｌｅｘｉｎｇ，ＷＤＭ）是利用一根光纤同时传送两种以上信号的一种通信方式，与微波通信中的频率分割多路传输方式相对应。在不同波长的光上载不同的信号，并用一根光纤传输它们，故能...     

通信光纤传输中的波分复用技术应用

随着光纤技术的飞速发展 ,一些先进的光纤通信技术应运而生 ,光纤的传输容量、传输距离、传输复用技术有了新的突破 ,笔者结合工作实践 ,着重分析用一条单芯光纤同时传输数字和模拟电视信号的波分复用技术。1　系统介绍由于部队机关至两家属区距离较远 ,为了当地有线电视节目的传输和线路设备的充分利用 ,现已架设有本单位机关至两家属区通信光纤上、下行各 1芯 ,如图 1所示。为了利用现有的通信光纤传输有线电视信号 ,在保证通信质量的前提下 ,用通信的一条单模光纤的两个窗口 ,分别传输 1310ｎｍ数字通信信号和 15 5 0ｎｍ模拟有线电视信…     

光电自适应通信技术在频谱监测中的应用

介绍了一种机载环境中光电自适应以太网通信技术在频谱检测中的应用,通信介质采用光纤和电缆双冗余热备份自适应的连接方式。光纤和电缆同时接入网络,通常情况下光纤作为主要的通信介质,当光纤链路发生故障时自动切换到电缆上,不影响系统的连接和中断系统的传输,提高了机载设备数据通信的灵活性和可靠性。对频谱监测的工作流程和光电自适应通信的原理进行了详细的描述,并对硬件和软件设计、调试方法及试验应用结果进行描述。     

浅析光纤通信工程中对光缆线路敷设的应用

光纤通信工程指的是将光纤作为传输的介质,并且诶运用多个光缆来进行光纤信号的传输工作,从而实现整个通信信号的多路传输.近年来,随着我够国民经济的不断发展,使得拥有信息量大以及传输速度快等优点的光纤通信技术也在全国范围内得到了广泛的应用,并且得到了良好的应用效果.而光缆线敷设作为光纤通信工程中的一个重要组成部分,其安装质量往往直接影响到了该光纤工程的整体施工质量.本文就对光纤通信工程之中的光缆线路敷设施工进行了分析.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks