利用双晶体实现的低频保偏光纤声光移频器

该文介绍了一种低频保偏光纤声光移频器的设计、制作、性能参数及典型应用。采用双晶体反向级联设计,将两片晶体工作频率的差值作为器件的移频频率,避免了单片声光晶体难以实现低频声光移频的问题。样品获得的性能参数为:工作波长1 053nm,移频频率10 MHz,插入损耗3.3dB,光上升时间33ns,输出偏振态线偏振。     

一种高速光纤声光调制器

该文介绍了应用于光纤传感系统中的高速光纤声光调制器的设计和应用。分析了影响光纤声光调制器调制速度的因素,介绍了高速光纤声光调制器的设计方法。最后采用氧化碲(TeO_2)晶体和小束腰光纤准直器得到工作波长1 550nm、光脉冲上升时间23.9ns、插入损耗2.9dB、通断消光比53dB的高速光纤声光调制器。     

单偏振光纤声光调制器

该文介绍了一种全光纤耦合的单偏振声光调制器的设计及应用。理论分析了光纤声光调制器的工作原理,描述了单偏振光纤声光调制器的关键指标(插入损耗、消光比、光脉冲上升时间)的设计方法和单偏振光纤准直器的耦合工艺方法。设计制作了工作在1.06 μm波长的高速低插损单偏振光纤声光调制器,其偏振消光比达到42 dB,能有效隔离系统偏振噪声。     

间接式光纤声光移频器

介绍了间接式光纤声光移频器的设计、结构和研究制作。在１．３μｍ光波长下，用单模光纤耦合，获得了移频频率５０ＭＨｚ±０．１ＭＨｚ、频率稳定度优于１０－５／ｈ、插入损耗－１０．９８ｄＢ和性能稳定的实验结果     

一种具有偏振保持能力的光纤耦合声光器件

该文报道了一种具有偏振保持能力的光纤耦合声光器件,对声光介质及保偏光纤的偏振特性进行了分析,并对器件设计思路及性能参数进行了介绍。样品器件采用TeO2作为声光介质;PM980光纤作为耦合光纤;在工作波长1 053nm、频率100 MHz下获得插入损耗为2.4dB、通断消光比为50dB、偏振消光比为22.24dB。     

基于差频原理的声光移频器

描述了声光移频器的特点及应用,依据一般声光移频器移频频率大于20MHz的局限性,提出了一种基于差频原理的声光移频器,介绍了其工作原理、光路设计及电路设计,在1 550nm波长下,得到了衍射效率>60%,移频频率±1MHz,频率稳定度优于10-6/2h的测试结果。     

基于磷化铟材料的高速光纤声光调制器

该文介绍了一种基于磷化铟(InP)材料制作的高速光纤声光调制器,分析了高速光纤声光调制器设计原理。通过仿真得到高速光纤声光调制器的设计参数,并制作了光波长为1 550 nm的300 MHz光纤声光调制器。测试结果表明,该光纤声光调制器的插入损耗为2.8 dB,消光比为49 dB,光脉冲上升时间为6.34 ns。     

一种高性能的光纤声光调制器级联模块

通过采用外部时钟、双路延时可调等技术,得到了一款工作波长1 550 nm、移频频率80 MHz、插入损耗5.4 dB、消光比＞100 dB、脉冲抖动1.8 ns的高性能光纤声光调制器级联模块。采用该级联模块搭建了M-Z干涉光路,得到了稳定的干涉波形。结果表明,该级联模块可提升光脉冲消光比,同时能有效地提升干涉波形的稳定性,对微弱信号探测的外差激光相干探测系统性能提升有一定的促进作用。     

一种低脉冲抖动高速光纤声光调制器

该文分析了调制后光脉冲信号时域抖动的机理,并介绍了低脉冲抖动光纤声光调制器的设计方法。实验验证表明,在波长1 550 nm下可得到光脉冲抖动为1.3 ns,光脉冲上升时间为7.9 ns,插入损耗为2.9 dB,消光比为56 dB的高性能光纤声光调制器。     

采用移频反馈的SOA多波长光纤环形激光器

文章报道了一种基于移频反馈的半导体光放大器(SOA)多波长光纤环形激光器,其环腔内插入声光调制器作为移频器,用自制的光纤马赫-曾德干涉仪进行梳状滤波,在输出光谱1.5 dB带宽为21.7 nm范围内,获得了间隔50 GHz的54个稳定的多波长连续光激射,消光比为28 dB.该激光器具有工作稳定性好、输出光谱宽和不同波长功率平坦度高的优点.实验证明,移频反馈技术能够实现激光器不同起振波长间的增益均衡,使输出光谱带宽增大21.7%.     

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.     

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.     

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.