铌酸锂微晶的光控制取向行为研究

基于光镊机理与倒置显微成像方法成功实现了铌酸锂微晶颗粒的光学捕获控制和光致取向的直接观测.由于铌酸锂微晶具有光学各向异性性质,所以在线偏振飞秒激光的操控下,所捕获的铌酸锂微晶颗粒能够依据激光偏振方向成功实现光控制取向.分析了铌酸锂微晶颗粒的激光控制取向机理,说明了铌酸锂微晶颗粒的取向可以利用激光的线性偏振方向进行光致取向旋转,有望应用于微纳光子学、MEMS、光控微型马达和微操作等科学研究领域.     

铌酸锂微晶的光控制取向行为研究（英文）

基于光镊机理与倒置显微成像方法成功实现了铌酸锂微晶颗粒的光学捕获控制和光致取向的直接观测.由于铌酸锂微晶具有光学各向异性性质,所以在线偏振飞秒激光的操控下,所捕获的铌酸锂微晶颗粒能够依据激光偏振方向成功实现光控制取向.分析了铌酸锂微晶颗粒的激光控制取向机理,说明了铌酸锂微晶颗粒的取向可以利用激光的线性偏振方向进行光致取向旋转,有望应用于微纳光子学、MEMS、光控微型马达和微操作等科学研究领域.     

铌酸锂微纳米结构的制备与分析

为实现铌酸锂光学器件的高效集成，在其表面制备亚波长结构是实现其光学特性的最佳方式。然而，目前使用的聚焦离子束刻蚀、激光刻蚀、湿法刻蚀等方法很难简单、经济、较快地制备铌酸锂亚波长结构。鉴于此，本课题组基于有限元仿真及低能离子束刻蚀技术，研究了不同离子束参数下刻蚀的铌酸锂亚波长结构及其透射率。采用Lambda950分光光度计和原子力显微镜分别对刻蚀后的铌酸锂样品的透射率、均方根粗糙度、纳米结构的纵向高度和表面形貌进行了分析。结果表明：当离子束入射角度为70°、入射能量大于600 eV、束流大于40 mA、刻蚀时间大于60 min时，铌酸锂样品表面形成了大面积的锥形纳米结构，并且纳米结构的高度随着离子束刻蚀参数的增大而增大；在可见光波段，铌酸锂表面纳米结构越高，增透效果就越明显；当入射能量为1000 eV、离子束束流为40 mA、入射角度为70°、刻蚀时间为120 min时，铌酸锂表面刻蚀出了纵向高度为143.5 nm的锥形结构，此时在可见光范围内铌酸锂样片的峰值透射率为83.5%，相较于原片的透射率提高了约12.5个百分点。     

铌锑酸镁陶瓷的烧结和微波介电性能

用固相反应法制备了一系列铌锑酸镁(Sb含量x≤2)陶瓷,研究了该陶瓷的烧结性能、物相结构和微波介电性能。结果表明,当x≤1.6时,铌锑酸镁形成了连续固溶体,少量Sb5+对Nb5+的取代(0.4≤x≤0.8),使得陶瓷最佳烧结温度从1400℃降到1300℃,而材料εr和Q·f值没有降低。1300℃,5h烧结的铌锑酸镁陶瓷具有优异的微波介电性能:εr为11.61,Q·f为169820GHz,τf为–54.4×10–6℃–1。     

熔盐法制备柱状铌酸钾钠粉体及其陶瓷

采用二步熔盐法合成了柱状铌酸钾钠粉体,并制备了致密的铌酸钾钠陶瓷。首先使用少量KSr_2Nb_5O_(15)粉体作为晶种,以Nb_2O_5、KCl与不同SrCO_3和Nb_2O_5的摩尔比(x=0.2,0.4,0.6和0.8)为原料合成了分散性较好的铌酸钾前驱体;然后将该前驱体通过化学拓扑反应制备出柱状的铌酸钾钠粉体;最后利用该粉体为原料,制备了铌酸钾钠陶瓷。测试结果表明,SrCO_3的添加有利于形成分散性良好的铌酸钾前驱体;Sr含量对钨青铜结构前驱体到钙钛矿结构铌酸钾钠的相转变有显著影响:当x≤0.4时,前驱体全部转化为钙钛矿相;x>0.4时,前驱体转变不完全;x=0.8时,前驱体几乎未发生转变。x=0.4时,合成的铌酸钾钠颗粒为微米级,长径比约为12,具有较高的烧结活性,为织构陶瓷的制备提供了一种合适的模板籽晶。     

周期性极化掺镁铌酸锂晶体光参量振荡研究

为了实现高转化率3m红外激光光参量振荡输出,采用外加脉冲电场法在厚度为1mm、掺摩尔分数为0.05的镁铌酸锂晶体上成功制备了周期为31.2m的极化光栅,理论计算并模拟了1064nm激光抽运周期极化铌酸锂晶体时,闲频光波长随温度的对应关系,并进行了实验验证。利用1064nm声光调Q Nd:YAG激光器作为抽运源对样品进行了光学参量振荡实验,其中,脉冲激光脉宽为200ns,重复频率是20kHz。在控制温度为80℃、输入抽运光功率为5.567W时,光参量振荡输出波长3m的闲频光功率为1.141W,光光转换效率达到20.1%。结果表明,通过此方法制备的周期性极化铌酸锂晶体光参量振荡,具有较高的光光转换效率。     

晶体和陶瓷中的压电效应与电致伸缩效应

本文根据热力学理论和晶体对称性,讨论了石英晶体的压电效应,也讨论了钛酸钡晶体和钛酸钡陶瓷,以及铌酸锂晶体的压电效应与电致伸缩效应.并论证了石英晶体具有“直接压电效应”;钦酸钡晶体和钦酸钡陶瓷具有“等效压电效应”;铌酸锂晶体具有“直接压电效应”和“等效压电效应”.     

单晶铌酸锂薄膜的转移制备技术研究

以苯并环丁烯(Benzocyclobutene,BCB)作为键合层,采用离子注入剥离技术制备了Y36切型的单晶铌酸锂薄膜材料。经过对BCB键合层的前烘时间和退火曲线进行系统的研究,克服了由于铌酸锂和BCB之间热膨胀系数不匹配所导致的铌酸锂薄膜开裂问题,获得了高质量的Y36切型单晶铌酸锂薄膜材料。此外,通过在晶圆键合之前预先制备图形化的金属层,获得了带有下电极功能层的单晶铌酸锂薄膜,可应用于薄膜体声波谐振器等具有金属-绝缘层-金属结构的器件。     

高能强场太赫兹源与铌酸锂晶体

高能强场太赫兹（THz）源在国土安全、通信雷达、生物医疗等领域有重要的应用价值。然而，一直以来THz源的辐射输出能量小、转化效率低，阻碍了强场THz前沿科学与应用研究的发展。基于铌酸锂倾斜波前技术，飞秒激光抽运铌酸锂晶体有望实现能量更高的极端强场THz输出。从材料角度阐述了铌酸锂强场THz源产出的研究进展，总结了强场THz源对铌酸锂晶体的性能要求：均匀掺镁铌酸锂、低浓度掺镁近化学计量比铌酸锂、大口径铌酸锂晶体。最后，介绍了近年来周期极化铌酸锂和铌酸锂单晶薄膜等微纳结构的调控在THz源领域的应用研究。     

电镀金刚石内圆切割刀片

1产品介绍 电镀金刚石内圆切割刀片产品主要用于切割脆硬材料,如:硅单晶、锗单晶、钽酸锂、铌酸锂、钕铁硼和陶瓷等材料.     

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.     

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.     

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.     

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