新型光纤信号调制器

在对光纤回波损耗研究的基础上，设计了一种基于多光束干涉效应的新型光纤信号调制器。实验中，利用两光纤端面间的多光束干涉作用，通过压电陶瓷控制两光纤端面的振荡距离，从而在输出端得到被调制过的光信号。这种光纤信号调制器主要针对信号振幅调制，调制比约为10％，信噪比约为60dB，带宽约为200kHz。该调制器展现了一种新颖的设计思路，可应用于光纤传输信号的调幅及光纤光源交流和脉冲信号的输出等。     

基于压电陶瓷光相位调制器的光纤微分干涉仪

基于压电陶瓷的逆压电效应,采用压电陶瓷作为光相位调制器设计了光纤微分干涉仪。理论分析和实验结果表明,干涉仪输出光强的幅度和频率与施加在压电陶瓷上的交变信号电压的幅度和频率有关,且在一定的条件范围内呈良好的线性关系。这种采用压电陶瓷作为光相位调制器的干涉仪具有线性范围广,灵敏度高等特点,可应用于对外界环境振动源的监测或用于检测压电陶瓷自身的动态特性。     

基于PZT陶瓷谐振技术的光纤相位调制器研究

分析影响了基于压电陶瓷谐振换能器的光纤相位调节的主要参数,并根据参数研制出一种满足性能要求的压电陶瓷光纤相位调制器.结果表明,光纤伸长位移量与光纤直径、压电常数、工作电压及陶瓷直径有关,与压电陶瓷的厚度无关;压电陶瓷光纤相位调制器的具有工作频率高(100 kHz以上),驱动电压低(2～3 V),电容小,介电损耗小,自滤波谐振等特点.     

压电陶瓷光纤相位调制控制系统的研制

压电陶瓷光纤相位调制器是光纤傅里叶变换光谱测量系统中的核心器件之一,压电陶瓷驱动控制系统的输出电压特性决定了压电陶瓷光纤相位调制器的多种性能,如线性、分辨率、动态特性等,从而对光纤傅里叶变换光谱测量系统的光谱分辨率、测量速度和系统噪声等重要指标产生影响.应用复杂可编程逻辑器件(CPLD)、复合高压运放和单片机等先进电子技术设计压电陶瓷光纤相位调制控制系统.实验表明,该系统加载压电陶瓷容性负载后,在设定的频率范围内显示出了较好的动态特性与线形度,能很好地满足光纤相位调制技术对压电陶瓷工作电压波形的要求.     

基于回波干涉效应的新型光纤信号调制器

理论分析了光纤信号传输系统中光纤端面菲涅耳反射所引起回波的多光束干涉效应,计算了光纤端面的反射回波相干叠加后回波光强随光纤端面间距的变化,针对光的振幅调制设计了基于回波干涉效应的新型光纤信号调制.实验中,从光纤耦合器输入端输入光波,将调制信号以电压形式加载于压电陶瓷管,使其伸缩振荡来控制两光纤端面间距离,光信号在光纤端面发生菲涅耳反射产生回波并发生回波干涉效应,从光纤耦合器回波端得到回波信号.实验结果表明,这种光纤信号调制器获得调制度约为95%,信噪比约为10 dB,带宽约为200 kHz.     

压电陶瓷相位调制器相移系数的测量

压电陶瓷相位调制器广泛应用于光纤测量系统中.本文介绍了利用光纤Michelson干涉仪测量医电陶瓷相位调制器的原理并实际测量了它的相移系数,同时对影响它的相移能力的因素进行了分析,为研制相位型光纤传感器奠定基础.     

压电陶瓷相位调制器相移系数的测量

压电陶瓷相位调制器广泛应用于光纤测量系统中．本文介绍了利用光纤Michelson干涉仪测量压电陶瓷相位调制器的原理并实际测量了它的相移系数,同时对影响它的相移能力的因素进行了分析,为研制相位型光纤传感器奠定基础．     

科技简讯

1.锁相二极管激光器阵列光束能量汇集德国斯图加特大学和空间宇航中心的研究人员合作成功地进行了将19个低功率单横模二极管激光器共同锁相的实验.二极管激光器阵列中的激光器用一个主二极管激光器锁相在入,阵列激光器的输出光束耦合入分立的保偏光纤,每条光纤都具有压电陶瓷相位调制器.对所有光纤输出光束进行准直,并构成6角形阵列光束.从组合光束分出一小部分光与主激光器发出的光干涉以提供相位反馈信息.每个激光器必须在相位控制环路的控制之下.     

磁致伸缩材料被覆保偏光纤磁场传感研究

通过直流磁控溅射镀膜,将磁致伸缩材料———铽镝铁被覆在一段去掉保护层的保偏光纤上,得到铽镝铁被覆保偏光纤结构的磁传感单元。采用保偏光纤及保偏光纤器件,建立马赫-曾德尔光纤干涉仪,将铽镝铁被覆保偏光纤结构的磁传感部分接在干涉仪的一臂中间,另一臂中接入保偏光纤绕制的压电陶瓷调制器进行光纤干涉系统的相位控制。该系统通过压电陶瓷调制器将相位控制在正交工作点上,解决了系统的相位衰落;全保偏光纤结构有效控制了系统偏振诱导的信号衰落,实现了系统对信号的稳定检测。实验得到了系统在不同大小直流偏置磁场作用下的磁场响应特性,结果表明,较大直流偏置磁场可使系统响应灵敏度提高约20倍,最小可测的交流磁场信号达到2.2×10-8T。     

Rogowski线圈的FBG电流传感器研究

电流是电力设备进行计量、监控和保护的重要参量,对其准确测量是电力系统安全、稳定、可靠和经济运行的保证。研制了一种Rogowski线圈、叠堆压电陶瓷和光纤Bragg光栅组合成的测量大电流的电流传感器。利用Rogowski线圈把高压侧大电流线性地转换为低电压,输出电压加在叠堆压电陶瓷上,由逆压电效应,叠堆压电陶瓷伸缩带动光纤Bragg光栅伸缩,将叠堆压电陶瓷的应变线性转换为光纤Bragg光栅的中心反射波长的移位,增加温补光栅消除环境温度的影响,通过测量光纤Bragg光栅中心反射波长的移位来测量电流的大小。测试结果表明,该电流传感器的灵敏度为0.071 8pm/A,非线性误差为3.47%FS,滞后误差为4.17%FS,重复性误差为4.17%FS。     

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.