厄米-高斯波束对各向异性圆柱的散射特性研究

为了研究厄米-高斯波束在各向异性媒质中的散射特性，采用了将各向异性圆柱的散射场和内部场用圆柱矢量波函数展开，应用电磁场边界条件和投影法，提出了一种分析单轴各向异性圆柱对厄米-高斯波束散射特性研究的精确半解析方法; 获得了厄米-高斯波束通过单轴各向异性圆柱的内场以及近场的归一化强度分布图; 对两种不同的厄米高斯波束入射情形做出了分析和对比。结果表明，两种波束在通过圆柱后都有入射波和反射波叠加而成的驻波现象，而TEM₁₀(x′)模式厄米-高斯波束入射后近场强度增强，且有明显的折射现象。该研究结果对厄米-高斯波束的应用具有一定的参考价值。     

光诱导光学晶格中高斯型孤子的开关行为

讨论了高斯型空间光孤子在光折变介质光学晶格的传输行为,运用分步傅里叶变换法对传输方程进行数值分析.研究表明:单个斜入射高斯型光孤子在周期性光学晶格中会局限于入射波导传输或在合适振幅的情况下穿过若干波导再自陷于某个波导;而当同时存在正入射和斜入射孤子时,两者相遇后会发生反射或透射,并可通过斜入射光孤子的振幅选择反射或透射.     

单层和多层有缝金属板电磁波透射的FDTD分析

采用在入射波一侧的总场边界处同时引进入射波和反射波作为激励源的FDTD方法来分析斜入射时单层和多层有缝金属板电磁波透射问题.通过计算金属板缝隙附近的散射场,提取缝隙口径面上的等效面磁流,进而得到透射截面.计算机仿真结果证实了算法的有效性.数值计算结果表明,两金属板上所开缝隙的相对偏移以及两板间插入介质板将会改变屏蔽效应.该方法可以有效分析平面波斜入射时多层金属板上任意形状缝隙的散射和透射,包括缝隙内或金属板之间填充有介质情形.     

圆偏振光在手征负折射材料表面的反射和极化特性研究

从理论上分析了圆偏振光入射到手征负折射材料表面的反射与透射特性,给出了归一化反射透射功率与入射角的关系曲线以及布儒斯特角与手征参数之间的关系曲线.当入射角大于两个本征波的临界角时,全内反射现象发生.由于手征负折射介质中的一个本征波发生了负折射,右旋或左旋圆偏振光入射时反射波的极化态有着与常规介质完全不同的特性,以布儒斯特角入射时反射光都为线偏振波但极化方向并不相同.     

复杂城市环境三维高斯波束跟踪预测模型

针对现有高斯波束跟踪预测方法认为绕射效应由波束扩展叠加体现而忽略绕射波束的问题,提出一种基于三维高斯波束的复杂城市环境电波传播损耗预测模型,该模型通过几何光学和几何绕射理论实现绕射波束的跟踪,并应用复射线理论和启发式有限导电率介质劈一致性绕射系数公式实现绕射场强计算.文中还分析了传播距离、反射次数等因素对电波传播预测精度和复杂度的影响.数值仿真结果表明:渥太华城市传播环境下考虑绕射预测精度比传统高斯波束跟踪模型高0.02~2.2dB,计算效率下降8%~10%;由于反射损耗、传播距离及波束扩展等因素,预测精度在反射次数取12时较高.     

二维fBm分形分层介质粗糙面电磁波透射特征研究

该文运用微扰法研究了平面波入射分层介质粗糙面的电磁波透射问题,推导出不同极化状态的透射波散射系数公式。采用二维fBm分形粗糙面来模拟实际的分层介质粗糙面,结合其功率谱导出了平面波入射时的透射系数计算公式。通过数值计算得到了HH极化状态下二维fBm分形分层介质粗糙面透射系数随透射波的散射角变化的曲线,分形特征、基本特征、随频率变化的特征。结果表明分维、底层介质介电常数、中间介质介电常数和厚度、粗糙面参数及入射波频率对透射系数的影响是非常复杂的。     

电磁场教学中的电磁波斜入射问题讨论

本文针对电磁场课程教学中一个容易混淆而缺乏充分论述的问题：斜入射电磁波在两种媒质分界面的反射和透射进行了深入的讨论,介绍了平面波、均匀平面波和非均匀平面波的概念。通过这个问题的讨论可以更全面的理解均匀平面波和非均匀平面波的概念及电磁波在无耗和有耗媒质中的传播特性。     

高斯光圆柱太赫兹雷达散射截面的影响

通过对缩比模型的太赫兹波段雷达散射截面(RCS)测量,可以获得微波波段全尺寸目标的RCS值,因此,RCS估算和测量是当前太赫兹重要的应用技术之一。RCS估算中,通常假定入射光为均匀平面波,但在实际测量应用中,常常采用发射类似高斯光束的太赫兹源。进行了横电波情况高斯光束入射时,无限长理想导体圆柱的太赫兹雷达散射截面估算。仿真研究了2.52 THz激光准直入射和相位变化对后向雷达散射截面的影响,给出了RCS与散射角的变化曲线;同时与均匀平面波入射结果进行了比较分析。仿真结果表明,在测量圆柱半径10 mm且入射光距圆柱轴心距离1 m处的后向RCS时,用光斑半径30 mm的高斯光束较好。     

斜入射角度调谐滤光片的反射光强分布

基于多光束干涉原理,从高斯光束在自由空间的传输方程出发,推导了高斯光束斜入射角度调谐窄带滤光片的反射光强以及透射光强的表达式。在此基础上研究了滤光片入射角对高斯光束反射特性的影响和关系。理论数值计算和实验结果都表明,随着入射角度的增大,滤光片透射光强的光斑会出现明显的展宽现象,而其反射光强的光斑虽会在较大角度斜入射时出现一定的展宽,但是展宽幅度远小于透射光斑的变化。故角度调谐窄带滤光片的反射端口在其调制范围内不需要跟透射端口一样进行光斑整形处理。     

基于平面波斜入射的人体信道远场路径损耗建模

人体信道路径损耗计算对植入式通信链路预估具有重要意义.文章利用有耗媒质的电磁场边界条件、反射和透射定理并引入切向等效波阻抗定义,推导出平面波向人体斜入射时各人体组织分界面上的入射角、透射角、反射系数、透射系数、切向等效波阻抗以及各人体组织中的电磁合成波,提出了一种基于平面波向多层有耗媒质斜入射的人体信道远场路径损耗解析模型.然后以植入在肌肉为例,计算了TM波和TE波在5个常用工业通信频率以不同角度斜入射的人体信道电磁场分布与路径损耗,结果显示,电磁波在入射面的反射是影响人体信道路径损耗的关键因素,当频率在1.4 GHz附近时总路径损耗最小,TM波性能优于TE波,且当入射角小于等于30°时,总路径损耗基本保持不变.最后采用COMSOL Multiphysics建立了有限元仿真模型验证解析模型,二者结果高度吻合,最大误差仅为0.039,有力证明了解析模型的正确性和有效性.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks