性能优良的光泵垂直腔面发射激光器

光泵半导体（OPS）激光器是一类以特殊类型垂直腔面发射激光器（VCSEL）为基础的新型器件，与以电流注入驱动的垂直腔面发射激光器不同，光泵垂直腔面发射激光器是用二极管泵浦激光驱动的。这种器件具有所希望的性能特性组合，如小型组件的高功率和优良TEM00模特性的组合。这种技术还可做成具有特定波长输出的激光器或在850～1600nm光谱范围可调谐的激光器。这些特性意味着光泵半导体激光器具有渗透或影响许多商业化激光应用开发的潜力，其中包括在通讯方面的应用。这方面的一个重要例子是泵浦高功率掺饵光纤放大器（EDFA）。光泵光泵…     

新型材料InGaNAs的生长与应用前景

详细介绍了一种新型半导体材料(InGaNAs)的生长特点及其在制作高特征温度的长波长量子阱激光器、长波长垂直腔面发射激光器、长波长光泵垂直外腔面发射激光器、半导体可饱和吸收镜和长波长谐振腔增强探测器方面的优势。     

二维光子晶体对面发射激光器横模控制研究

垂直腔面发射激光器的单模输出特性在光网络数据传输光互连、光存储和激光打印中有重要的应用.传统的氧化限制型垂直腔面发射半导体激光器由于串联电阻大、发热严重而很难工作在单模状态.二维光子晶体结构可以有效地控制垂直腔面发射激光器的横向模式,使器件工作在单模状态下.从理论上系统研究了光子晶体垂直腔面发射半导体激光器的单模条件,成功设计了一组单模光子晶体垂直腔面发射半导体激光器,并通过常规工艺制作出功率0.6 mW、边模抑制比大于30 dB、阈值电流4 mA、远场发散角8.4°、不受电流注入影响的单模光子晶体垂直腔面发射半导体激光器.实验证明:光子晶体可有效地进行横模控制.     

外部光反馈对980nm垂直腔面发射激光器振荡特性的影响

研究了外部光反馈对980nm垂直腔面发射激光器(VCSEL)振荡特性的影响.计算了垂直腔面发射激光器及边发射半导体激光器的光反馈灵敏因子.基于复合腔理论,分析了外部光反馈对垂直腔面发射激光器的阈值电流及微分量子效率等振荡特性参数的影响.实验结果表明,当反馈率为10%时,垂直腔面发射激光器的阈值电流由0.63A下降至0.59A,同时斜率效率和输出功率也有所下降.实验结果和理论分析符合得较好.     

微小孔阵列垂直腔面发射激光器的研究

在980nm波长的大功率垂直腔面发射激光器(VCSEL)的基础上制备了高输出功率的微小孔阵列半导体激光器,其最大输出光功率达到了1mW。介绍了针对微小孔阵垂直腔面发射激光器的特殊制备工艺,并对其特性进行了分析。     

垂直外腔面发射半导体激光器的热管理方法研究

垂直外腔面发射半导体激光器在高功率运转的同时可以保持良好的光束质量,近年来一直成为研究的热点。本文介绍了垂直外腔面发射半导体激光器的结构及运行原理。由于热管理是其高功率运行的主要限制因素之一,分析了垂直外腔面发射半导体激光器的热管理方法。使用反向生长的外延片通过化学湿法腐蚀去掉砷化镓衬底,得到了约6μm左右的外延片,最后利用808nm的泵浦光进行抽运获得了200mW的连续激光输出。     

量子阱垂直腔面发射激光器及其微腔物理

根据发展历史的顺序,对量子阱垂直腔面发射激光器微腔物理进行了概述,其中包括垂直腔面发射激光器、腔量子电动力学和半导体微腔物理。给出半导体垂直腔面发射激光器及其微腔物理思想来源的详细图像。     

量子阱垂直腔面发射激光器及其微腔物理

根据发展历史的顺序,对量子阱垂直腔面发射激光器微腔物理进行概述,其中包括垂直腔面发射激光器、腔量子电动力学和半导体微腔物理。给出半导体垂直腔面发射激光器及其微腔物理思想来源的详细图像。     

光子晶体垂直腔面发射激光器特性研究

本文介绍了光子晶体垂直腔面发射激光器的制备工艺、工作原理、基本特性和研究进展,重点评述了光子晶体垂直腔面发射激光器的优良特性及应用前景.我们认为光子晶体垂直腔面发射激光器是一种新型的半导体激光器,它具有大出光孔径、较高的出光功率、稳定的单模、多芯传输等特点,而且具有优良的热特性和高速调谐特性,可在二维光信息处理的GaAs基近红外波段激光器、面阵集成等方面具有很大的应用潜力.     

半导体可饱和吸收镜锁模光抽运垂直外腔面发射半导体激光器

介绍了半导体可饱和吸收镜锁模光抽运垂直外腔面发射半导体激光器的原理、基本结构特点、应用及设计中的主要问题，对其研究进展及未来发展趋势作了分析和总结。     

X-ray metrology for high-k atomic layer deposited HfxZr1−xO2 films

Hafnium-based dielectrics are the most promising material for SiO₂ replacement in future nodes of CMOS technology. While devices that utilize HfO₂ gate dielectrics suffer from lower carrier mobility and degraded reliability, our group has recently reported improved device characteristics with a modified Hf_xZr_1−xO₂ [R.I. Hegde, D.H. Triyoso, P.J. Tobin, S. Kalpat, M.E. Ramon, H.-H. Tseng, J.K. Schaeffer, E. Luckowski, W.J. Taylor, C.C. Capasso, D.C. Gilmer, M. Moosa, A. Haggag, M. Raymond, D. Roan, J. Nguyen, L.B. La, E. Hebert, R. Cotton, X.-D. Wang, S. Zollner, R. Gregory, D. Werho, R.S. Rai, L. Fonseca, M. Stoker, C. Tracy, B.W. Chan, Y.H. Chiu, B.E. White, Jr., in: Technical Digest - International Electron Devices Meet, vol. 39, 2005, D.H. Triyoso, R.I. Hegde, J.K. Schaeffer, D. Roan, P.J. Tobin, S.B. Samavedam, B.E. White, Jr., R. Gregory, X.-D. Wang, Appl. Phys. Lett. 88 (2006) 222901]. These results have lead to evaluation of X-ray reflectivity (XRR) for monitoring high-k film thickness and control of Zr addition to HfO₂ using measured film density. In addition, a combination of XRR and spectroscopic ellipsometry (SE) is shown to be a fast and non-intrusive method to monitor thickness of interfacial layer between high-k and the Si substrate.     

Students’ thoughts about the importance and costs of their mobile devices’ features and services

In recent years, handheld devices have become one of the fastest growing communication gadgets. Mobile technology is becoming widespread and research in this area is urgently needed. Using a survey instrument, the thoughts of male and female students regarding the importance and costs of mobile devices were investigated. It was found that students tend to consider the following features important: battery life, mp3 player, video camera, photo camera, storage memory, Bluetooth, design and elegance, clock, calendar, organizer and reminder. Also, they are eager to spend an amount of money so as their mobile device to support them. On average, both genders would pay extra money for such features. However, the majority of females think less of the price than males do. On the contrary, most of the respondents do not consider the following important: touch screen, voice commands, chat, teleconference, encryption and cryptography, common use of files, printing. Therefore, they would not spend any money for these features. Interested decision makers would try to increase their interest on such features. Moreover, all respondents appear to own a mobile phone while most of them do not have Internet connection at home. In general, some gender differences are found in the importance and costs of the mobile devices, but they are not statistically significant.     

Job schedulers for Big data processing in Hadoop environment: testing real-life schedulers using benchmark programs

At present, big data is very popular, because it has proved to be much successful in many fields such as social media, E-commerce transactions, etc. Big data describes the tools and technologies needed to capture, manage, store, distribute, and analyze petabyte or larger-sized datasets having different structures with high speed. Big data can be structured, unstructured, or semi structured. Hadoop is an open source framework that is used to process large amounts of data in an inexpensive and efficient way, and job scheduling is a key factor for achieving high performance in big data processing. This paper gives an overview of big data and highlights the problems and challenges in big data. It then highlights Hadoop Distributed File System (HDFS), Hadoop MapReduce, and various parameters that affect the performance of job scheduling algorithms in big data such as Job Tracker, Task Tracker, Name Node, Data Node, etc. The primary purpose of this paper is to present a comparative study of job scheduling algorithms along with their experimental results in Hadoop environment. In addition, this paper describes the advantages, disadvantages, features, and drawbacks of various Hadoop job schedulers such as FIFO, Fair, capacity, Deadline Constraints, Delay, LATE, Resource Aware, etc, and provides a comparative study among these schedulers.     

Progress in ZnO materials and devices

ZnO is a wide-band-gap semiconductor material that is now being developed for many applications, including ultraviolet (UV) light-emitting diodes, UV photodetectors, transparent thin-film transistors, and gas sensors. It can be grown as boules, as thin films, or as nanostructures of many types and shapes. However, as with any useful semiconductor material, its electrical and optical properties are controlled by impurities and defects. Here, we consider various important donor-type impurities, such as H, Al, Ga, and In, and acceptor-type impurities, such as N, P, As, and Sb. We also examine the effects of a few common point defects, including Zn interstitials, Zn vacancies, O vacancies, and complexes of each. The main experimental techniques of interest here include temperature-dependent Hall-effect and low-temperature photoluminescence measurements, because they alone can provide donor and acceptor concentrations and donor energies. The important topic of p-type ZnO is also considered in some detail.     

Thyristor Input-Protection Device Suitable for CMOS RF IC’s

Based on simulation results and accompanying analysis, we suggest a thyristor-type ESD protection device structure suitable for implementation in standard CMOS processes to reduce the parasitic capacitances added to the input nodes, which is very important in CMOS RF ICs. We compare DC breakdown characteristics of the suggested device to those of a conventional NMOS protection device to show the benefits of using the suggested device for ESD protection. The characteristic improvements are demonstrated and the corresponding mechanisms are explained based on simulations. Structure dependencies are also examined to define the optimal structure. AC simulation results are introduced to estimate the magnitude of reduction in the added parasitic capacitance when using the suggested device for ESD protection. The analysis shows a possibility of reducing the added parasitic capacitance down to about 1/45 of that resulting with a conventional NMOS protection transistor, while maintaining robustness against ESD.Jin-Young Choi was born in Seoul, Korea in 1956. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the M.S. and Ph.D. degrees in electrical engineering from the University of Florida, USA, in 1986 and 1991, respectively. In 1991, he joined Samsung Electronics Memory Division, Korea, where he was engaged in high-speed SRAM development. In 1992, he moved to the Hongik University, Jochiwon, Korea, where he is now an associate professor. His recent research interests include the high-frequency modeling of CMOS devices, CMOS RF circuit design, and analysis & design for ESD protection.Woo Suk Yang was born in Seoul, Korea in 1957. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the Ph.D. degree in electrical and computer engineering from the North Calorina State University, USA, in 1990. His doctorial research was in the area of signal processing. In 1990, he joined LG Electronics Co. Korea. In 1991, he moved to the Hongik University, Jochiwon, Korea, where he is now a professor. His recent research interests include the high-frequency modeling and various topics in signal processing area.Dongmin Kim was born in Korea in 1956. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea, in 1979 and 1984, respectively and the Ph.D. degree in ECE from the University of Michigan, USA, in 1996. Now, he is an assistant professor of the Hongik University, Jochiwon, Korea. His recent research interests include circuit design and analysis.Youngju Kim was born in Seoul, Korea in 1957. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea in 1980 and 1985, respectively and the Ph.D. degree in electrical engineering from the Polytechnic University of New York, USA, in 1995, respectively. In 1996, he joined the Hongik University, Jochiwon, Korea, where he is now an assistance professor. His recent research interests include the RF circuit design and LIN wireless systems.     

智能语音操控在广电端到端的系统设计及应用

在数字化中国的大背景下,在公司个人宽带与互动电视在线交费用户均突破300万户的情况下,为解决我们的用户总找不到自己喜欢看的节目,记不住频道名称和喜欢的节目,提升公司竞争力。通过对前端的点播系统、AAA系统、EPG系统、PORTAL系统、ISMP系统、媒资系统、机顶盒终端的功能进行剥离、整合和详细设计,最后完成终端用户语音操控电视直播、点播、时移、回看、页面操控、系统设置,并支持普通话和四川话方言的目的。达到提升用户体验,增加公司竞争力,促进业务的发展。系统试运行后,用户体验效果得到很大提升,完全达到预期设计目的。     

谈对电子元器件企业设计开发过程中“六性”的审核

通过对电子元器件企业＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂的审核,帮助企业识别＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂,认识＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂在产品设计开发中的重要性,实现产品的＂可靠性、维修性、保障性、测试性、安全性和环境适应性＂指标。     

A Progress Report on Metal–Sulfur Batteries

Nonaqueous conversion‐reaction sulfur chemistry has been attracting increasing attention over the past decade for the development of next‐generation lithium‐based batteries. Li–S batteries are currently approaching a nexus stage from lab‐scale experiments to possible pragmatic applications. Inspired by the success of Li–S chemistry, other metal–sulfur batteries with a variety of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum, have also started to attract attention. In comparison to lithium, Na, Mg, Al, K, and Ca are naturally more abundant and affordable. The Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S battery systems provide a great potential for improving the volumetric energy density of sulfur‐based batteries. The multivalent metal‐sulfur systems, Mg‐S, Al‐S, and Ca‐S, offer better safety features as well. However, the research and development on Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S batteries is far behind the Li–S system due to many critical challenges. In this progress report, the fundamental principles of various metal–sulfur chemistries are first presented and compared. Then, the historical progress, recent advances, and key challenges of the Li–S, Na‐S, Mg‐S, Al‐S, K‐S, and Ca‐S systems are summarized and discussed. Finally, future efforts and directions for both the fundamental and practical research are prospected.     

VoIP技术--语音和数据的集成

介绍了VoIP(Voice over IP)的基本组成构件即网关(Gateway)、网守(Gatekeeper)的概念和用途。讲述了语音在IP网上传输的基本原理，语音和数据、数据和IP包之间的转换和传送过程。在H．323协议栈的基础上详细讲述了H．248，H．225，H．245等通信协议和语音编码G．729，G．23l，G．7ll等协议。最后对VoIP的语音服务质量作了较为详细的阐述。     

An Integrated Model to Design PCS Networks

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management’s point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach. Salah M. Ramadan (samohra@yahoo.com) received the BS and MS degrees from Computers Engineering Department, Al-Azhar University, Cairo, Egypt, in 1995 and 2002, respectively. From 2002, he was a PhD student in Computers Engineering Department at Al-Azhar University and is currently pursuing the PhD degree, where he is a research assistant in the Wireless Networks Branch. His research interests include traffic management in ATM networks, routing protocols, mobility management in PCS networks, and mobile computing. He is currently an instructor in Cisco Academy, Egypt. Ahmed M. El-Sherbini (Sherbini@mcit.gov.eg) received the Ph.D. in Electrical and Communication Engineering, Case Western University, U.S.A. March 1983 and M.Sc. in Communication Engineering, Cairo University, Giza, Egypt, June 1980. (M.Sc. Research Studies at the Ecole Nationale Superieure des Telecommunications (ENST), Paris, France) He is the Director, National Telecommunication Institute – Ministry of Communications and Information Technology, Egypt and Professor of Electrical and Communication Engineering Dept. Faculty of Engineering, Cairo University, Egypt. M. I. Marie(azhar@mailer.scu.eun.eg) received his B.Sc, M.Sc and PhD in electronic and communication engineering from Cairo University on 1972, 1981, 1985, respectively. Now he is a professor of communications at Computer and System Engineering Department Al-Azhar University, Cairo, Egypt. His fields of interest includes digital communication, computer networks and protocols development. M. Zaki is the professor of software engineering, Computer and System Engineering Department, Faculty of Engineering, Al-Azhar University at Cairo. He received his B.Sc. and M.Sc. degrees in electrical engineering from Cairo University in 1968 and 1973 respectively. He received his Ph.D. degrees in computer engineering from Warsaw Technical University, Poland in 1977. His fields of interest include artificial intelligence, soft computing, and distributed system.