纳米光通信技术的核心--纳米光电子器件

本文概述了纳米技术在光电领域的应用,并着重介绍国内外纳米光通信用纳米光电子器件的发展现状。     

纳米通信技术的核心纳米光电器件

概述了纳米技术在光电子领域的应用，并着重介绍了国内外纳米光通信用纳米光电子器件的发展现状。     

纳米通信技术的核心纳米光电器件讨论

纳米技术将通信带进了一个新的时代,大大推进了通信技术的发展。如今,纳米通信技术已经成为通信系统中必不可少的组成部分。文章将就纳米通信技术中的核心纳米光电器件进行详细的讨论。     

水下LED光通信技术研究与实现

通过电路硬件设计与软件程序设计,提出了一种水下低功耗LED光通信系统,可以实现水下节点之间的半双工模式高速通信.实测结果验证了本系统可完成水下距离达10m、速率达115.2kb/s的低误码通信.     

近距离无线激光通信系统的设计

研究了一种用于传输数字图像信号的近距离无线激光通信系统,对系统的发射机和接收机部分进行了电路设计,搭建了实验系统并进行了系统调试,得到了合适的电路结构和器件参数,为实用的无线激光通信系统的研究和设计提供了参考依据。     

光导型光电探测器瞬变行为的仿真

较强功率的激光辐照半导体探测器时既产生光电效应又产生热效应，提出了反映光电效应的载流子输运模型和反映热效应的热扩散模型。计算了不同激光辐照功率密度下PC型HgCdTe探测器内的光生载流子浓度和热平衡载流子浓度．由此对探测器的瞬变行为进行了仿真计算。仿真结果与实验结果相吻合。     

自由空间光通信中光电子器件的现状分析

对自由空间光通信中的光电子器件包括激光器、光电探测器、光学滤波器的现状做了系统分析，结果表明：CO2激光器、半导体激光器和LD泵浦的YAG固体激光器成为目前和未来自由空间光通信系统的重要光源；PIN和APD光电二极管成为自由空间光通信系统探测器的最佳选择；干涉滤波器和原子滤波器成为自由空间光通信系统滤光器的发展重点。     

采用纳米压印技术制作DWDM激光器的研究

 适合DWDM系统应用的高性能DFB半导体激光器是现代光通信系统中发射机的核心光电子器件,光栅的设计和制作是决定器件性能的关键因素之一。目前,基于MOCVD设备的材料外延技术趋于稳定,高速器件封装技术也已经成熟,满足DWDM需求的DFB光栅的加工渐渐成为进一步降低成本的一个瓶颈。本文利用纳米压印技术制作DFB激光器光栅。结果表明,利用纳米压印技术制作出来的DFB激光器性能不逊于用EBL直接制作出的高性能激光器,不仅可以满足DWDM系统的要求,而且还具有生产效率高、成本低的优点。     

Design of reversible parity generator and checker for the implementation of nano-communication systems in quantum-dot cellular automata

Complementary metal-oxide semiconductor (CMOS) technology may face so much problems in future due to the smaller size of transistors and increase in circuits’ volume and chips temperature. A new technology that can be a good alternative to CMOS circuits is quantum-dot cellular automata (QCA). These technologies have features such as a very low power consumption, high speed and small dimensions. In nano-communication system, error detection and correction in a receiver message are major factors. In addition, circuit reversibility in QCA helps designs a lot. In this research, generator and checker circuit of the reversible parity and eventually their nano-communication system are designed reversible using odd parity bit. The proposed circuits and the theoretical values are tested by QCADesigner 2.0.3 simulator to show the correct operation of the circuits. According to the simulation results, the proposed circuits compared with the previous structure improve delay by 90–75–35% in generator and checker structures of parity and their reversibility of nano-communication system, respectively. The proposed circuits are used in nano-transmitters and nano-receivers.

     

Progress in electrophotography in Western Europe

A review is given of the progress in electrophotographic science and technology in Western Europe during the years 1967 to early 1971. University research work is mainly directed towards two areas: 1) the electrical and physical properties of photoconductors, such as selenium, chalcogenides, oxides, and organic materials; and 2) the sensitization of these photoconductors. Industrial research teams report on the preparation of electrophotographic layers on development and on image evaluation. A bibliography including scientific papers and patents published on this subject during said period completes this review.     

智能通信在楼宇自控系统中的应用

随着计算机技术、控制技术、通信技术及信息技术的飞速发展,人们对生活、办公环境安全性、舒适性的要求日渐增长,智能建筑应运而生。楼宇自动化控制系统是智能建筑的一个重要组成部分。通过结合具体的智能楼宇控制工程项目,在介绍系统概况的基础上,给出了系统的总体设计方案及子系统的监控方案,具有一定的实用价值。     

Advances in millimeter-wave subsystems in Japan

The authors describe the development trends and results of millimeter-wave systems in Japan in such fields as communication, radar, and measurement systems. The applications included are the W-40G waveguide transmission communication system, an automobile traffic control system using the 60-GHz band, a collision avoidance radar system for an automobile, a plasma electron density measuring system, and satellite communication. The authors describe the development of devices such as high-power FET amplifiers, traveling wave tube amplifiers (TWTAs), IMPATT amplifiers, low-noise amplifiers, and monolithic microwave integrated circuit (MMIC) devices used in constructing the millimeter-wave systems     

Two-wave mixing in reflection holograms in photorefractivematerials

The intensity and phase of two counterpropagating optical beams in a photorefractive material are investigated both numerically and by using an approximate analytical theory. It is shown that in the reflection regime they are two situations where coupling between the beams may be spatially dependent; in the case of nearly degenerate two-wave mixing, and when a photocurrent is present. In these situations, previously obtained results may need significant correction     

Propagation in Broadside-Coupled Suspended-Substrate Stripline in E-Plane

The spectral-domain analysis is applied to the derivation of the propagation characteristics of the even and odd mode, for the broad-sidecoupled suspended-substrate stripline (BCSSS). The characteristic impedance, based on the current-power definition, as well as the effective permittivity are evaluated. Numerical results are presented illustrating the effects of several different dimensional parameters. Numerical results indicate a large spread between even- and odd-mode impedance for thin substrates (D/A < 0.045) and stripwidths ranging 0.046<= W/B<= 0.47, suggesting tight coupling. Negligible frequency dependence on odd-mode impedance is evident, as well as significant frequency effects on even-mode impedance. Considerable dispersion is shown to be present in the odd mode for wider strips. Measured results for a low-pass filter and cascaded transitions are presented.     

Autosolitons in InSb in a magnetic field

It is shown experimentally that a longitudinal magnetic field of comparatively small magnitude substantially changes the velocity of autosolitons in indium antimonide samples and produces an appreciable redistribution of the electric field of these autosolitons. In this case, the frequency and amplitude of the current oscillations in the external circuit of the sample increases or decreases, depending on the direction of the longitudinal magnetic field. Fiz. Tekh. Poluprovodn. 32, 697–700 (June 1998) An erratum to this article is available at .     

Errors in reprojection methods in computenzed tomography

Iterative tomographic reconstruction methods have been developed which can enforce various physical constraints on the reconstructed image. An integral part of most of these methods is the repro. jection of the reconstructed image. These estimated projections are compared to the original projection data and modified according to some criteria based on a priori constraints. In this paper, the errors generated by such reprojection schemes are investigated. Bounds for these errors are derived under simple signal energy assumptions and using probabilistic assumptions on the distribution of discontinuities. These bounds can be used in the enforcement of constraints, in the determination of convergence of the iterative methods, and in the detection of artifacts.     

RECENT PROGRESS IN MULTI—BEAM KLYSTRON IN IECAS

Recent research progresses in Multi-Beam Klystron(MBK)in IECAS are briefly introduced in the letter,The S-band MBKs of IECAs have peak power of 120-250kW,average power of 4-9kW,efficiency of 35-45%,gain of 41-46dB.beam voltage of 15-19kV,and weight of 40-45kg.Some key technical problem of MBK are also described and discussed.Among them,improving the design of MBK to botain the required bandwidth,raising beam transmission to increase average power,eliminating oscillation and spray spectrum,overcoming window breakdown caused by magic mode,reducing breakdown times of electron gun,are most important things for the practical MBK.Besides,further research owrk in MBK in IECAS is commented.