城市光网中异常发光ONU检测技术创新思路——上海“城市光网”技术创新和应用实践之九

在全力推进“城市光网”建设的过程中,由于软件或硬件等原因造成的异常发光ONU故障严重影响了PON承载的业务质量,已经成为危害PON稳定运行的主要故障之一.但是异常发光ONU故障定位存在一定难度,给PON维护带来不小的压力,因此,尽快研究并提出一套行之有效的异常发光ONU检测方法,将为推动城市光网的发展产生重要的作用.本文通过对异常发光ONU的故障原因及检测机制进行深入分析和研究,提出了一种创新型故障检测思路.     

PON网络弱光问题分析与防护

PON网络中的弱光问题随着FTTX业务发展(远距离、大分光比应用)变得越来越严重。通过对弱光产生原因的分析,梳理了影响光功率预算的主要因素。基于EPON扩展OAM/GPON OMCI协议,通过比较标准定义与实际应用,报告了ONU光功率的检测方法以及对应的弱光故障定位策略。结合工程应用总结了弱光问题防护与解决的几种方法。     

异常发光ONU故障新型检测技术研究

异常发光ONU(光网络单元)故障严重影响EPON(以太无源光网络)的正常运行,已经成为危害EPON稳定运行的主要故障之一。文章通过对异常发光ONU故障检测技术的研究背景及故障原因的深入分析,提出一种基于硬件采集的新型异常发光ONU故障检测技术。该检测技术从硬件底层出发,对EPON网络进行链路层监测,为异常发光ONU的故障维修提供一套有效的解决方案。     

一种跨OLT的PON保护技术

目前已经实现的无源光网络(PON)保护方案通常保护的是光线路终端(OLT)的PON媒体接入控制器(MAC)到光网络单元(ONU)的PON MAC之间的光路,无法对OLT整体设备进行保护.文章介绍了一种跨OLT的PON保护方案:ONU同时在两台OLT上注册,两台OLT之间通过传输控制协议(TCP)方式使配置和状态等信息周...     

PON中异常发光ONU的检测技术研究

PON规模运营后,由于其多用户共享上行带宽的技术特性,使得异常发光ONU成为网络运营中的凸显故障.本文主要介绍现网中发现的典型故障,分析异常发光ONU的产生原因,并且结合实际网络运维经验,对PON设备能力提出了技术要求,提出了适用于现网的异常发光ONU的检测机制和流程.     

PON业务常见故障的处理

无源光网络(PON,Passive Optical Network)采用无源光分/合路器或光耦合器分配/汇聚各光网络单元(ONU,Optical Network Unit)信号的光接入网。PON系统系由光线路终端(OLT,Optical Line Terminal)、光分配网(ODN,Optical Distribution Network)、光网络单元(ONU)组成的信号传输系统,简称PON系统。目前主流PON综合接入系统根据采用的技术分为以太网无源光网络(EPON,Ethernet Passive Optical Network)和吉比特无源光网络(GPON,Gigabit-capable Passive Optical Networks)。     

基于小波包变换码的新型无源光网络上行信号复用和传输方法

提出了一种基于小波包变换正交码的多电平正交编码的无源光网络(PON)中上行信号复用和传输新方法,将PON系统中各个不同的光网络单元(ONU)用户用小波变换正交码来进行调制、复用和传输,能够实现各个不同ONU用户共享一个波长。由于采用了小波变换编码,可以实现数量很多ONU用户同时上行,在ONU端不需要突发光模块以及多波长激光器,因而成本低,传输速率高,接入数量多。给出了基于该方法的上行系统调制、复用和传输的结构模型,并仿真了传输速率为1.25Gb/s和10Gb/s下不同路ONU用户上行传输,仿真结果表明,最大可以实现上行32路,每路10Gb/s,总传输速率达到320Gb/s的高速PON系统。     

广电宽带常见故障分析与排除

数据信号自县局前端机房核心路由器经汇聚机房的汇聚交换机发送至本地机房OLT,再从OLT的PON口经分光器送至各ONU,采用1490nm(下行)、1310nm(上行)光信号.数据信号从光节点到用户采用2种接入方式:EPON+LAN(五类线进户),EPON+EoC(低频EoC,同轴电缆进户).采用EoC方式的,在光节点处将ONU、光接收机连接到EoC头端混合后经分支分配器送至EoC终端,EoC终端再与电脑连接.采用LAN方式的,ONU经交换机通过五类线送至用户电脑. 由于ONU是绑定在OLT的PON口下,EoC头端、楼道交换机都配有远程管理IP地址的功能,可远程管理并查看运行状态,发生故障后,可请播出机房人员配合远程查看、判断、处理相关故障,可根据不能上网也不能看电视、能看电视但不能上网等情况,初步判断是A网还是B网的问题.     

PON网络终端发展趋势

从多个角度分析了目前现网中家庭用户使用的ONU+HG组网模式的不足,并提出采用集成家庭网关型ONU(HGU)设备解决此组网模式存在的问题。从维护管理的角度,分析了HGU设备的两种网管方式(PON网管和PON网管+TMS网管)的优缺点,指出采用PON网管和TMS网管结合的方式对HGU设备进行远程管理是较为理想的方式。最后阐述了ONU设备的发展趋势。     

无源光网络语音业务仿真技术研究与实现

基于PON(无源光网络)技术的光纤宽带网络正在快速发展,传统PSTN(公共交换电话网络)语音业务正逐步被基于PON的多业务统一接入替代,如何快速高效地完成PON承载的语音业务故障诊断是服务提供商面临的难题。文章介绍了基于PON的语音业务组网特点和实现流程,分析了语音业务故障诊断的需求,设计了一种利用ONU(光网络单元)模拟语音呼叫信令的技术方案。实际测试表明,该方案能够模拟用户完成语音呼入呼出操作,自动分析语音呼叫故障原因,简化了语音业务故障处理流程,提升了服务效率。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.