一种改进的智能化EDFA设计

提出了一种改进的智能化掺铒光纤放大器(EDFA)结构.通过详细的仿真研究,得出该结构EDFA的设计依据.在16波长、每信道-30dBmW小信号输入时,平坦增益37dB、最大噪声指数小于3.5dB;大信号输入时,平坦增益18dB、最大噪声指数小于5dB.使用该结构的EDFA具有很大的输入动态范围和稳定、平坦的输出特性,能自适应地工作于前置放大、功率放大和线路放大状态,有利于在密集波分复用(DWDM)光网络中的应用.     

C波段增益平坦掺铒光纤放大器的优化设计

EDFA的增益不平坦是限制DWDM系统性能的一个重要因素,目前已经提出了许多方案来改善EDFA在整个C波段内的增益谱.采用双级串联结构,并在两段光纤中间加入增益均衡滤波器来实现增益平坦.通过对前后两段铒光纤的长度优化,使得增益均衡滤波器的谱特性易于实现.优化后的EDFA输出功率达到17dBm,噪声指数小于5dB,在1530～1565nm的带宽内增益波动小于1dB.     

长距离DWDM系统中EDFA的研制

采用光纤光栅和增益平衡器等光无源器件 ,在常规掺铒光纤放大器 ( EDFA)内部引起光反馈和滤波整形机制 ,研制成功多信道动态增益均衡 EDFA,锁定工作波长带宽 17nm( 1544～1561nm) ,在输入功率 - 2 0～ - 5d Bm内增益恒定为 2 3d B,噪声系数小于 5d B,输出功率 18d Bm,并进行了 80 0 km× 8× 2 .5Gb/ s长距离 DWDM信号高速传输的实验研究 ,在信道数改变的动态运行情况下 ,系统误码率达 10 -10 。     

密集波分复用系统中级联EDFA光信噪比分析

文中推导出级联 EDFA密集波分复用系统光信噪比表达式 ,并由 EDFA噪声指数的定义推导出级联 EDFA系统等效噪声指数的表达式 ,分析了级联 EDFA系统输出端 OSNRout与等效噪声指数之间的关系 ,通过实验对其进行了验证     

DWDM系统中级联EDFA光信噪比计算

本文推导出级联EDFA密集波分复用系统光信噪比表达式,并由EDFA噪声指数的定义推导出级联EDFA系统等效噪声指数的表达式,分析了级联EDFA系统输出端OSNRout与等效噪声指数之间的关系,并通过实验对之加以了验证。     

基于单个光纤光栅反射技术的高性能L波段EDFA

基于单个光纤光栅反射技术提出一种高性能L波段EDFA。用一个光纤布拉格光栅(FBG)反射EDFA产生的一部分C波段放大自发辐射(ASE)噪声,该部分ASE噪声被重新注入到掺铒光纤中以提高增益效率。用静态均衡器平坦输出的增益谱,在L波段范围内,增益被箝制在25.5dB,增益不平坦度小于0.5dB,噪声指数小于5.5dB,为DWDM系统提供了一项有效的解决方案。     

增益平坦滤波器的几种实现技术

EDFA的增益平坦化是DWDM系统中的关键问题,介绍了EDFA增益平坦滤波器的实现技术原理并对其关键技术参数进行了比较,认为啁啾光栅增益平坦滤波器是--较好的选择.试验表明,在高功率EDFA中加入啁啾光栅增益平坦滤波器,其增益平坦度可控制在±0.3dB以内.     

基于级联光纤环形镜的增益平坦掺铒光纤放大器

基于光纤环形镜的滤波原理,提出利用级联结构光纤环形镜(FLM)实现掺铒光纤放大器(EDFA)增益平坦滤波的方案,并进行了相关实验研究.实验结果显示,使用级联FLM取得了明显的增益平坦效果,其1535-1557nm波长范围内的增益不平坦度由±5dB减小到±1dB.     

光子晶体增益平坦滤波器的设计

掺铒光纤放大器(EDFA)的增益平坦化是波分复用(WDM)系统中的重要问题.提出了用光子晶体实现增益平坦的新方案.通过分析EDFA增益平坦的原理与一维光子晶体的反射谱(在不同波长处具有不同反射率的特性),设计出了满足特定条件的增益平坦滤波器.以EDFA典型曲线为例,利用遗传算法简便精确地优化一维光子晶体的周期数,从而设计出了与EDFA增益谱相匹配的增益平坦滤波器.结果表明,级联的一维光子晶体滤波器在1530～1560 tim范围内对EDFA的增益进行平坦,且不平坦度约为±0.6 dB.     

掺饵光纤放大器测试系统研制

报导了用积木式设计方法、由下列几部分组成的一套以拟合技术为基础的掺饵光纤放大器( EDFA)测试系统 :1低边模抑制波长和功率可调光源 ;2测试控制单元 ;3单色光功率计 ;4控制与数据采集和处理微机系统 ;5专用机柜 ;6系统控制与测试数据采集和处理软件。该系统可以测量EDFA的增益 G、噪声指数 NF和光功率 P等参数及其与波长λ的关系。波长测量范围是 1530～1570 nm,精度为± 0 .1nm;G和 N F的测量不确定度分别为± 0 .5d B和± 0 .7d B;光功率的测量精度为± 0 .2 d B。在这套系统中用“单色光功率计”代替了价格昂贵的光谱分析仪 ,并开发有良好的测试与控制系统软件 ,使该系统成为一套适用性与经济性很好、操作使用灵活、简单快速的 EDFA测试系统     

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.     

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.