HFC网中EDFA的应用研究

在HFC光网络段中,可利用EDFA来延长系统的传输距离.采用优化设计法对HFC网络进行工程设计,就其对HFC网络性能指标影响展开讨论.分析表明:加入EDFA后,对CSO,CTB基本没有影响,而对CNR影响较大,当光网络距离小于294 km时,可以不考虑色散的影响.     

HFC网中EDFA的应用研究

在HFC光网络段中，可利用EDFA来延长系统的传输距离。采用优化设计法对HFC网络进行工程设计，就其对HFC网络性能指标影响展开讨论。分析表明：加入EDFA后，对CS0，CTB基本没有影响，而对CNR影响较大，当光网络距离小于294km时，可以不考虑色散的影响。     

CATV光网络设备原理及应用第十三讲 EDFA的结构及原理

(上接第03/04期) 自从英国南安普敦大学D.Payne等科学家发现掺铒光纤可以作为1 550 nm波长区的光放大器,并研制出第一台具有25 dB的小信号增益的掺铒光纤放大器(EDFA)后,由于各国科学家的努力,今天的EDFA大量商用于各类光纤通信系统,极大地推动了光纤系统应用的发展,可以说EDFA的出现是光纤通信技术上的一场大变革.EDFA直接对光信号进行放大,可以显著增大中继距离,使超长距离传输成为可能、实行波分复用提高系统传输速率成为现实,实现光时分复用以至光弧子通信传输前景更加明朗.EDFA在HFC接入网中应用,能有效补偿光功率分配损耗,扩大覆盖范围,降低成本造价.总之,EDFA商用化是光纤传输网补偿光衰减,实现高速率、超长距离和大覆盖面的重要手段.     

掺铒光纤放大器在市县联网工程中的应用

1 概述 在有线电视系统传输距离不太长时,可根据同轴电缆的特性,采用分支分配结构构成较为经济的电视电缆系统。而在有线电视传输距离较远、范围较大时,通常采用光缆、电缆构建HFC网络,在HFC网络的光纤部分也可利用分支器件来搭建成本较低的系统。实际应用中,通常采用光分支来实现同一光源带更多的光节点。同时为使光信号传输距离更远,必须对光     

全光网节点规模的分析

导出了光信噪比与光节点数量 ,掺铒光纤放大器 (EDFA)噪声系数 ,增益的关系公式 ,并分析了光节点数目与EDFA特性参数的关系。分析表明 ,当光节点中EDFAs设置成输入EDFA补偿节点损耗 ,输出EDFA补偿光纤损耗的工作方式时 ,要保持光信号的信噪比不低于 2 0dB ,则光节点数目最多为 19左右 ,改善EDFA的噪声系数对提高光节点数目的作用不大 ;如降低光节点内部损耗 ,优化两个EDFA的增益 ,可以最大程度地提高网络节点规模 ,网络节点数最大可达 5 6。     

一种新型光放大器

掺铒光纤放大器(EDFA)是WDM光通信网络最关键技术之一,它对光信号传榆的距离和信号传输的完整性起着决定性的作用.文章对EDFA的发展作了一定的阐述,主要介绍一种新型EDFA的设计理念、控制策略的选定、功能的实现情况以及电路和软件的设计情况,它是一种具备动态均衡调节功能和监测功能的新型光放大器.     

用EDFA提高激光雷达的信噪比

提出了掺铒光纤放大器(EDFA)应用于激光雷达接收系统光学前置放大器以提高雷达探测性能和作用距离的方法.回波信号功率是影响雷达探测分辨率的因素,它随着探测距离的增大而减小.讨论了光电检测前放大回波信号的技术,结合激光雷达回波信号的特点对EFDA主要应用特性(增益特性、噪声特性)进行理论分析.建立了雷达信号传输模型,讨论了大气消光与大气湍流对回波信号的影响.将PIN-FET用作光电探测,给出了没有采用光放大和采用EDFA光学前置放大情况下的信噪比.数值模拟结果显示,将EDFA用作激光雷达接收机极大地提高了雷达系统的信噪比,探测距离越远探测性能的改善越明显.     

PBN：EDFA1550nm掺铒光纤放大器，19″-1RU

EDFA光放大器是为MATV、CATVFTTH和CCTV宽带应用而设计的。 该产品适用于长距离传输网络．采用固定的19″,1RU的标准机箱。EDFA光放大器光输出功率范围为20-200mW（13～23dBm）,     

HFC系统用掺铒光纤放大器的设计与测试

介绍了光纤同轴电缆混合网（HFC）中应用的掺铒光纤放大器（EDFA）的工作机理和性能特点;论述了在研制HFC系统用掺铒光纤放大器时,为了提高其性能而应该考虑的因素以及相应的措施,并且给出了其主要性能指标的测试方法和结果。     

1550nm波段光纤CATV传输系统的噪声分析及组网

对1500nm波段光CATV噪声的产生的机制进行了讨论.重点分析了EDFA产生的噪声特性,对系统载噪比(CNR)与EDFA输入功率之间的关系和系统CNR与调制指数的关系进行了研究,得出了提高CNR的方案;对光CATV组网方案进行了讨论,给出了一个光CATV网络设计的实例.     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.