A scheme for ultra-low-noise avalanche multiplication of fiber-optics signals

Current high-speed device structures have carriers traveling across submicrometer device dimensions under the influence of extremely high electric fields. This gives rise to avalanche multiplication in a finite medium with only a few ionizing collisions per traversal of the primary carrier through the device. The finite medium avalanching results in less uncertainty in the gain process and hence a promise of low-noise avalanche multiplication.     

国内光纤光缆通信市场研究报告

光纤通信市场的基本情况我国从1994年开始，光缆中的光纤芯数出现明显增大的趋势。1999年以前光纤的年增长率均保持在40%以上，市场规模超过30亿元。2000年中国国内光纤需求量达世界第三，光纤市场共550万芯公里，市场总额在45亿元左右，除了电信公用网的高速增长外，各类专用通信网的建设也驶入了快车道。根据国内光纤市场的发展，光纤市场用量持续增长，未来3年的平均复合增长速率将保持在35%以上，依此估算得出实际用量和预测值增长变化情况如图1所示。今后3年，我国光纤光缆需求量将急剧增加。从图1中可以看出，2001年中国对光纤的年需…     

Laser primer for fiber-optics users

The basics of semiconductor lasers are reviewed. Specifically, lasers with wavelengths between 1.3 and 1.55 μm, the range most applicable to fiber-optic communications, are discussed. In this range, light experiences lower loss on silica fiber; in addition, 1.3 μm is the wavelength of zero dispersion, where the refraction index and, consequently, the speed of propagation are independent of wavelength. Key properties of semiconductor lasers, including power-current characteristics, beam shape, spectra, modulation, noise characteristics, and reliability, are discussed     

基于光电倍增管的光子计数仪设计

在医学检验中,体内多类激素水平及其微量代谢产物、药物及代谢产物、维生素类及疾病相关抗原的分析测定总计可达几十至上百种之多.但由于其检测灵敏度要求较高,一般免疫技术难以达到.因此,长期以来一直使用放射免疫法.这不仅对操作人员的健康造成了危害,其废弃物对环境也有严重的污染.因此需要特殊的防护及废物处理系统;同时,由于受到自然衰变的限制,其试剂不便长期储存和运输,因而大大地限制了它的发展.     

光子技术实现了光纤与硅片的集成

由半导体开发商Luxtera公司（位于美国加利福尼亚州卡尔斯巴德）推出的CMOS光子技术可提供10Gb／s的光调制速率,从而能够将高速光纤接口与采用工业标准CMOS制造工艺所生产的硅器件集成在一起。通过减少昂贵Ⅲ-Ⅴ半导体的用量,该技术可为计算机和通信设备OEM制造商提供光纤通信的性能优势,并使成本和设备复杂性显著下降。     

Improvement of photon extraction efficiency of InGaN LEDs utilizing textured ZnO layer deposited by electrospray deposition

Improvement of photon extraction efficiency of InGaN LEDs has been achieved by deposition of textured ZnO layers on InGaN LED bare chips utilizing electrospray deposition. The electrical and spectral properties of the InGaN LED remain unchanged after the deposition of ZnO, while the InGaN LED with textured ZnO layer exhibits a wider far-field angular distribution. The optical power of the InGaN LED capped with ZnO layer is ∼30% higher than that without ZnO, which is due to increased photon escape probability as a result of the increased surface roughness.     

一种新型的光子交换

提出了一种基于副载波的光标记交换的方案和标记交换的原理,它是解决电子交换瓶颈的有效方法,将充分利用电子技术的成就解决低速标记交换的问题,同时保留了光包的高速和透明性不变。     

Influence of photon reabsorption on the transfer efficiency of output intensity in semiconductor microcavities

Photon reabsorption effect on the transfer efficiency /spl beta//sub t/ of half-wavelength semiconductor microcavities was investigated by examining the excitation intensity dependence of the output light intensity. It is shown that /spl beta//sub t/ increases under intense excitation, and approaches to over-all spontaneous emission coupling coefficient /spl beta//sub 0/, as a result of the elimination of photon reabsorption. The results clearly demonstrate that the photon reabsorption is the predominant mechanism of the suppression of /spl beta//sub t/ at weak excitation, especially in the case of half-wavelength high-Q cavities.     

A note on utilizing far-field phase information

The far-field phase information available from an antenna pattern is discarded in most system applications. Making use of such information for an angle-of-arrival estimation application across a relatively wide region of space is discussed in this note. The far-field phase difference response from two simultaneous shaped beam receive patterns generated by a linear array antenna is shown to provide an appropriate relative phase property for making unambiguous angle determinations.     

A millimicrosecond pulse-generator tube

This paper describes the theory and testing of a 100- Mc repetition-rate millimicrosecond pulse-generator tube utilizing klystron bunching. The optimum operation of the generator was obtained with a drift-tube transit angle Θ0of approximately 150°; depth of modulationalpha = V_{1}/V_{0} = 1; and the reduced plasma-anglePhi_{q}was less than 20°. Observations and data were determined with an Edgerton, Germeshausen and Grier traveling-wave oscilloscope and a comparison measurement technique. The generator has a measured pulse rise time of 130 µµsec (0-100 per cent), and a pulse duration of 300 µµsec at the half-voltage point. A pulse height of 20 volts on a 50-ohm coaxial line is possible. The analysis applied in predicting the shape of the pulse was based on large signal ballistic bunching theory and a quantized collector gap theory. A comparison between analysis and measurement indicates an error of about 20 per cent. Theory predicts that little improvement can be made in the pulse duration, but the pulse rise time may be improved with increased circuit complexity.     

A multichip package utilizing in-Cu flip-chip bonding

A multichip package is described which is composed of an alumina ceramic base, screen-printed gold and glass crossovers, photolithographically delineated copper conductors, a brazed on Kovar lead frame, indium-copper flip-chip bonded integrated circuit chips, and a glass-severa, interfaces between dissimilar metals, between metals and insulators, and between different insulators. The reasons for selection of the various materials for these interfaces are presented. The major innovation in this package, the indium-copper flip-chip bond, is discussed both from a processing viewpoint and from an analytical viewpoint, supported by diffusion, X-ray crystallographic, and metallurgical data.     

A study of photon emission from n-channel MOSFET's

It is known that an n-channel MOSFET, operating in the saturation region, is accompanied by visible light emission. The spectral distribution of this emitted light is reported in this paper for the first time. It behaves as exp (-α . hv) under various bias conditions (α: constant); the energy state of hot electrons is described as a Maxwell-Boltzmann distribution. The hot-electron temperature in an n-channel MOSFET is experimentally evaluated from the photon spectrum analysis. As compared with the electric field strength calculated by two-dimensional simulation, the hot-electron temperature is found to be determined as a function of the electric field strength in the drain avalanche region.     

A self-aligned counter-doped well process utilizing channeling ionimplantation

This paper describes a new self-aligned counter-doped well process realizing low junction capacitance CMOS's. This technology intentionally utilizes channeling ion implantation to achieve counter doping of the well in the same mask step as SD implantation. The benefit of this technology is its process simplicity with full compatibility with the conventional CMOS process. Applying this technology to a 0.25-μm CMOS process, a 50%-70% reduction in junction capacitance is achieved, and an 18.3% improvement in simulated propagation delay time is demonstrated for 0.25-μm CMOS inverter chains under 0.9-V operation     

A spectrally efficient PMR system utilizing broadcast service

Different trunked Private Mobile Radio (PMR) systems have been designed over the last several decades, all of which have symmetric downlink and uplink channel capacities. Due to this symmetry, these systems may not be spectrally efficient in case of different types of services, which are specific to PMR systems, such as group and broadcast calls. In this study, a new asymmetric trunked PMR system comprising a broadband, wide-area downlink and a narrowband cellular uplink, is proposed to achieve a higher spectral efficiency than current digital trunked PMR systems. This system is spectrally more efficient because in group and broadcast calls only a single downlink channel has to be allocated in the downlink part. However, as the number of clusters in the system increases, this advantage relative to PMR systems is lost, since the latter can employ frequency reuse. Spectral efficiency of the proposed asymmetric system (a-PMR) system and a standard TETRA system are compared using numerical case studies against different traffic loads and number of clusters. The optimum point, with respect to number of clusters, up to which the proposed a-PMR system is more efficient, is determined. It is shown that a very large PMR user population can be efficiently served using the proposed a-PMR system. The issues related to implementing such a system are discussed.     

（英）一种基于透镜天线的宽带太赫兹准光检波器

设计了一种能够工作在140~325 GHz频带的宽带准光检波器,由一颗高阻硅透镜和单片集成检波芯片组成.设计并加工出双缝天线,在天线馈电端集成了肖特基二极管,该紧凑结构使其能够接收空间中的太赫兹辐射并转换为基带信号.为增强片上天线的方向性,利用MLFMM算法进行了扩展半球硅透镜的设计和优化,实现了良好的辐射特性.通过测试,天线在220 GHz和324 GHz处的辐射增益分别为26 dB和28 dB.在140~325 GHz,检波器测试得到的响应率可达到1 000~4 000 V/W,对应的等效噪声功率(NEP)估算为0.68~273 pW/Hz.     

基于光电倍增管单光子脉冲幅度分布的多比特光量子随机源

提出并验证了一种基于光电倍增管单光子脉冲高 度分布的多比特光量子随机源。将紫外LED发出 的光衰减成离散的单光子序列,光电倍增管探测到的单光子后,输出脉冲幅度随机分布的单 光子脉冲,通 过数字化单光子脉冲的峰值作为熵源来提取随机数,实现了一个单光子事件产生多个随机比 特位。为减小 所提取原始随机数存在的偏差,提出并实现了基于FPGA的SHA-256后 处理方法。光量子随机源工作在 500kc/s时,平均每个探测光子可提取7bit随机位,获得了3.5Mbit/s的随机位产生速率。运用随机性 测试程序ENT和STS对所获的随机位序列进行测试,测试结果表明,序列的随机性满足真随机 数的标准。     

A ceramic-metal voltage reference tube

A glow discharge voltage reference tube constructed entirely of ceramic and metal has been developed. Minimum size (T2), extreme ruggedness, and unusual electrical stability characterize the tube. Operating voltage is approximately 85 v. Performance of the reference tube under conditions of shock, vibration, high temperature, and high altitude is described. Operating voltage stability over extended periods is demonstrated by presenting the results of precision measurements. Other aspects, such as temperature coefficient, ionization voltage, and the slope and smoothness of the voltage-current characteristic are discussed.     

A new high-performance color picture tube: The mask-focusing color tube

From a technical point of view, improvements of conventional color picture tubes could be regarded as having reached their limits. In this respect, we have found that the mask-focusing tube can achieve further improvements when combined with the black-matrix technique, a high-performance gun, dot screen structure, high-matrix transparency, and large gun electrode diameter. Two-fold improvements of brightness and contrast have been obtained with mask transparency twice that of conventional tubes, 22-percent higher matrix transparency, and mask-focusing. A 20-30 percent less deflection power has also been achieved with 110° deflection, neck diameter, and 1:2 mask-focusing voltage ratio. A 20-percent less spot diameter and a sharp beam distribution have been obtained by a new multistage-focusing electron gun in a delta arrangement in the 35.5-mm neck diameter.     

A low-noise He-Ne laser tube

A low-noise He-Ne laser discharge tube that eliminates discharge modulation noise is described. The noise levels, both in the discharge current and in the laser output, are suppressed by more than 40 dB when the discharge current is below 42 mA.