太赫兹Smith-Purcell自由电子激光研究进展

太赫兹电磁波在材料表征、医学成像、无线通信、安全检测等领域有广泛的应用前景,是当前科学研究热点之一。基于自由电子与周期性光栅结构相互作用产生的Smith-Purcell辐射的Smith-Purcell自由电子激光凭借其易加工、可调谐、高功率等优点成为发展高功率太赫兹源的有效途径之一。本文对太赫兹Smith-Purcell自由电子激光的近期研究进展进行了综述,对基于特异Smith-Purcell辐射新型Smith-Purcell自由电子激光以及基于预群聚电子注的Smith-Purcell太赫兹源进行了着重介绍,这两类新型太赫兹自由电子激光结构克服了传统自由电子激光的若干缺点,有望发展为具有重要应用前景的紧凑型、大功率太赫兹源。     

用于太赫兹真空器件的大电流密度阴极

主要介绍了太赫兹器件对电子源的需求,并对国际上各类适用于太赫兹器件的电子源进行了分析和对比.作者认为正在研发的热阴极和冷阴极(场发射阵列阴极)是未来太赫兹器件电子源的两个选择.目前,热阴极技术和场发射冷阴极也正在因为器件需求的推动而进一步发展,并已经取得了较好的成果.文章最后就北京真空电子技术研究所近年来的热阴极技术进展和场发射冷阵列阴极技术发展进行了简明介绍;所取得的技术成果表明,热阴极和场发射阵列阴极都具有广泛的太赫兹器件应用前景.     

石墨烯太赫兹波段性质及石墨烯基太赫兹器件

石墨烯在太赫兹波段的优异性质,使其在太赫兹源、太赫兹探测和太赫兹调控三个方面都具备广阔的应用前景。主要对石墨烯在太赫兹波段的性质及石墨烯基太赫兹器件的相关研究进行了综述,并对石墨烯在太赫兹波段的应用前景进行了展望。在石墨烯太赫兹波段性质方面,主要介绍了石墨烯的电导模型、静态和超快光谱响应特性,以及表面太赫兹波辐射特性。在石墨烯基太赫兹器件方面,主要综述了基于光、电、磁调控的太赫兹主动器件,石墨烯基超材料的太赫兹调制器,基于阻抗匹配的减反射调控器件,以及可调太赫兹源器件的最新研究进展。     

电子束团驱动矩形光栅增强Smith-Purcell辐射的研究

随着微纳加工工艺的进展,微纳周期结构的电磁特性成为了研究的热点.基于周期光栅结构的Smith-Purcell辐射机理,本文研究了矩形缺陷金属透射光栅的Smith-Purcell辐射机制,结果显示具有矩形缺陷的光栅能产生更强的辐射.这种通过构造矩形缺陷来提升辐射功率的方法在基于自由电子的太赫兹辐射源方面具有重要应用.     

偏置电压驱动下AlGaN/GaN二维电子气的宽谱太赫兹波发射

本文介绍了低温（6 K）下偏置电压加速AlGaN/GaN二维电子气产生的宽谱太赫兹波发射。根据“浅水波”等离子体波失稳理论和史密斯-珀塞尔理论,分别设计了两种器件结构。实验结果表明所观测到的太赫兹辐射与电子浓度无明显依赖关系,得到的而是自于晶格和热电子的黑体辐射。通过考虑湿度和衬底法布里-珀罗谐振腔作用,计算得到的热电子发射光谱与实验光谱良好吻合。研究结果表明通过电流驱动二维电子气产生太赫兹辐射的器件将不可避免地产生强烈的电子气加热和晶格加热问题,很难实现理论预言的等离子体波失稳与高效太赫兹发射。因此,需要设计更加精巧的器件结构才能实现高效的等离子体波激发和太赫兹发射。     

强激光太赫兹辐射源研究现状与发展趋势分析

太赫兹源在无线通信、光谱学、生物医学成像和材料科学等领域具有极高的应用价值。近年来,对高品质强太赫兹源的需求更为迫切,而有效产生高品质强太赫兹源仍然是太赫兹科学中的关键科学问题。概述了几种激光太赫兹源的产生机制以及发展现状：非线性晶体可以高效率产生太赫兹源,但受到晶体能量损伤阈值限制,难于在超强激光条件下工作;气体等离子体太赫兹源可以突破电离阈值的限制,但太赫兹能量会随着激光强度的升高而饱和,无法进一步提升太赫兹的场强;固体靶等离子体是相对论电子在等离子体中动力学行为产生的超强太赫兹辐射,并且可以通过结构靶等方式调制太赫兹品质,有望高效率地产生高品质强太赫兹源。最后,总结和展望了太赫兹源在应用领域的发展趋势。     

基于GaN/AlGaN高电子迁移率场效应晶体管的室温太赫兹探测器

本文主要论述一种带平板天线,基于GaN/AlGaN高电子迁移率场效应晶体管的室温太赫兹探测器。太赫兹辐射下,由于天线的作用会在栅下感应出平行沟道和垂直沟道的太赫兹电场,由此在源漏产生强烈依赖于栅压的直流光电流。尽管栅极远离源漏两端,平行沟道和垂直沟道的太赫兹电场依然很强。探测器可以用自混频理论很好的描述。在室温下,探测器的响应度和噪声等效功率分别为100 nW/sqrt（Hz）和 3 mA/W。探测器具有很高的响应速度,在5 KHz的调制下,光电流没有衰减。如果缩少栅极和源漏的距离将进一步提高探测灵敏度。     

太赫兹回旋管研究进展

回旋管是一种基于电子回旋谐振受激辐射的快波器件,是目前太赫兹波段输出功率和效率最高的重要器件,本文给出了目前国内外太赫兹回旋管技术的发展状况,分析了太赫兹回旋管的特点和应用前景.     

改进光电导太赫兹天线输出功率与方向的研究

光电导天线被广泛用于太赫兹波的产生,但是产生的太赫兹功率较低,方向性差。为了改进光电导太赫兹天线输出功率与方向,研究了不同基底厚度对光电导天线辐射功率的影响,其仿真结果表明:辐射功率受基底厚度影响明显,大部分辐射功率进入基底的一侧而不是自由空间,厚度薄的基底更能辐射出较大的功率。为了提高光电导天线的方向性,设计出一个加载在光电导天线输出端的锥形喇叭天线结构,仿真得到该喇叭天线的方向性为20.7dBi,这表明可以通过加载锥形喇叭,在期望的方向上获得较高的太赫兹波功率。     

源漏偏置电压对AlGaN/GaN HEMT太赫兹探测器灵敏度的调控

天线耦合的场效应晶体管(FET)太赫兹自混频探测器通常工作在零源漏偏压下,设置恰当的栅极电压可获得最佳的灵敏度.测试分析了天线耦合AlGaN/GaN高电子迁移率晶体管(HEMT)太赫兹自混频探测器的源漏偏置电压对太赫兹自混频响应度和噪声的调控作用.研究结果表明,源漏偏置电压在增强响应度的同时也大幅度增强了探测器输出的噪...     

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.     

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     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first