光伏电池表面抛物锥阵列微结构的反射特性研究

采用时域有限差分法(FDTD)对硅基太阳能电池表面抛物锥阵列微结构的反射特性进行研究,分析了抛物锥阵列的高度、底面占空比、周期等参数对其抗反射性能的影响。研究表明,反射率随底面占空比、高度的增大而减小。在锥高600 nm且抛物锥底面直径等于周期的情况下,锥底面直径分别取128,160,213,256,320 nm时,微结构在硅的响应光谱300~1200 nm内均能获得低于3%的反射率;在此基础上提出一种大、小抛物锥相切排列的新型复合结构,将硅的响应光谱波段内的反射率进一步降低至1%以下,为硅基太阳能电池抗反射表面的设计提供了一种新的思路。     

双周期嵌套微结构表面的抗反射特性

为提高红外材料光学表面的抗反射能力,设计了一种具有双周期嵌套式结构抗反射超表面。通过分析在双周期嵌套式结构周围的介电常数变化情况,仿真模拟得到反射率。重点分析了当微纳结构发生变化时这种嵌套结构与单一结构表面抗反射特性的差别。通过改变嵌套结构表面占空比、顶底端直径比以及长径比等参数仿真模拟,对抗反射特性进行分析,最终优化出的结构在2.4~12 m的超宽波长范围内反射率均低于3.5%,在中长波实用波段范围内平均反射率低于1%。这种结构有效地保护了微结构形貌不被破坏,实现了单一结构抗反射特性效果的叠加,进一步降低了元件表面的反射率,可以作为一种新型的减反增透表面应用于红外窗口。     

光子晶体光纤的多模色散特征

采用有效折射率模型对光子晶体光纤的多模色散参数进行了数值计算,给出了不同结构光子晶体光纤的多模色散系数随波长的变化关系,并对计算结果作出了合理的物理解释.     

Ge基底LaF3-ZnS-Ge高耐用中波红外增透膜

锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法（Finite Difference Time Domain）,并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12 μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11 μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。     

圆锥形仿生蛾眼抗反射微纳结构的研制

采用时域有限差分（FDTD）法对中红外波段（3~5 m）硅基底的圆锥形仿生蛾眼微纳结构进行了仿真模拟。通过对微纳结构占空比、周期和刻蚀深度等参数的分析,获得了具有良好抗反射特性的微纳结构的组合参数。为了更好地指导实际加工,对不同参数进行了公差分析。制作中应用二元曝光技术和反应离子刻蚀技术在硅基底上制备得到该圆锥形仿生蛾眼微结构,并且使用热场发射扫描电子显微镜得到了该微结构的表面形貌图。采用红外成像光谱仪对单面微结构的测试结果表明,仿生蛾眼微结构的反射率在中红外波段约为5%。     

双周期Bragg光纤的研究

本文在常规Bragg光纤结构的基础上提出一种双周期Bragg光纤,它的包层是由两个具有不同周期性结构的内外包层组成。利用传输矩阵法和渐进矩阵法相结合的方法,通过数值计算,理论分析了这种双周期Bragg光纤的损耗和波导色散特性.结果表明,它的泄露损耗随波长变化规律不同于常规Bragg光纤,而内包层的结构对波导色散有较大影响。     

Si衬底表面圆柱形抗反射周期微结构的设计及制作

应用严格耦合波分析方法(RCWA),在本征硅片衬底表面设计并制作了一种圆柱形抗反射微结构元件。通过MATLAB软件模拟仿真确定其最优参数组合,使反射率设计值为3%。应用二元曝光技术和反应离子刻蚀技术制作了单面和双面的圆柱形微结构,根据结果得到射频功率、气体流量及工作气压对微结构侧壁陡直度及形貌具有很大影响。还分析比较了形状(t为实际柱顶面直径与底面直径之比)与反射率的关系。采用热场发射扫描电子显微镜对该结构进行形貌表征,综合显微成像红外光谱仪对反射率进行测量。实验结果:制作了单面、双面微结构与无结构本征硅片反射率做比较双面圆柱形微结构的抗反射效果最好,反射率达8%左右,基本达到抗反射设计要求。     

光纤中的SBS反射率和波形研究

从理论和实验上研究了不同焦距下泵浦能量以及透镜与光纤间距对多模光纤中的SBS能量反射率和脉冲波形的影响。理论模拟采用一维瞬态SBS数值计算模型和边界噪声输入法，得到了SBS反射率和脉冲上升沿的变化规律。实验上采用1.06μm的YAG激光器和无掺杂多模阶跃石英光纤，测得了能量反射率和波形的变化规律，获得的最大反射率为69%，脉宽压缩比为3:1-2:1。计算结果与实验结果符合较好。     

多层纳米微结构的制备与陷光机理研究

采用电化学腐蚀方法在单晶硅片表面制备了折射率渐变的多层纳米微结构。用扫描电镜和UV-VIS-NIR分光光度计分别分析了多层纳米微结构的表面形貌和反射率。研究了腐蚀电流密度和腐蚀时间对微结构减反射性能的影响并分析了多层纳米微结构的陷光机理。结果表明:硅片表面的纳米孔径随着腐蚀电流密度和腐蚀时间增加而增大,初始腐蚀电流密度为12.25mA/cm2和腐蚀时间为2s时,表面最大的纳米孔径为30nm,在400nm～800nm的可见光波长范围内的反射率为3.4%,在200 nm～2000nm的宽波长范围内反射率仅为5.8%,远小于常规金字塔对应的反射率。这种宽波段范围的低反射率来源于多层纳米微结构中邻层相差很小的等效折射率。     

二维情形下组合激光辐照45~#钢靶温升效应的模拟

基于组合激光的新概念,对重频激光与连续激光组合辐照下钢靶的温升进行了数值计算.根据实验测得的钢靶时1.06μm连续激光的反射率随温度的变化曲线,通过求解二维轴对称热传导方程,比较了不同组合参数下钢靶的温升以及能量利用率,分析了组合激光的优势所在.计算结果表明:平均功率密度相同时,组合激光要比连续激光的加热效率高,加热效率还与组合激光中重频激光的各种参数相关,重频激光占空比为1%且峰值功率密度保持不变时,加热效率随着重频率的减小而增高.     

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.     

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.     

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.     

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