Heterojunction and heterodimensional devices for optoelectronics

This article features a few optical sensory devices with basic properties that are changed by the presence of a two-dimensional electron gas (2DEG). A photodetector based on ohmic contact to the 2DEG is first presented in which variation of the 2DEG concentration and the (transverse) electric field that causes this confinement radically changes the device behavior. Next, the same device architecture is used but two Schottky contacts replace the ohmic ones, resulting, as expected, in a vastly different device behavior     

Numerical techniques for modeling guided-wave photonic devices

Accurate modeling of photonic devices is essential for the development of new, higher performance optical components required by current and future high-bandwidth communications systems. This paper reviews several key techniques for such modeling, many of which are used in commercial design tools. These include several mode-solving techniques, the beam propagation method, the method of lines, and the finite-difference time-domain technique     

并联型无源与有源次同步振荡阻尼装置对比分析

提出了并联型FACTS装置抑制次同步振荡的无源阻尼与有源阻尼的概念。以静止无功补偿器和全控型换流器作为实现方法。采用复转矩系数法,分别推导了机端接入方式下,2种次同步振荡阻尼方法提供的阻尼系数和正阻尼条件,对比了影响二者提供正阻尼大小的相关因素。分析结果表明,无源阻尼的大小与阻尼装置接入点系统电压大小成正比,有源阻尼的大小则不受接入点电压大小的影响,而主要与其自身产生的次同步电压大小成正比。采用机端阻尼控制方式,分别对2种阻尼装置的控制器进行了设计。采用测试信号法,通过相位补偿,分别对阻尼装置提供的正阻尼进行了优化。时域仿真结果表明,对于短路故障引起的次同步振荡,在装置容量相同的情况下,有源阻尼方法较无源阻尼方法具有更强的阻尼能力。     

Optimizing active and passive countermeasures

In the context of bioterrorism, active countermeasures are those measures designed to deny an enemy the opportunity to launch or strike, and passive countermeasures are those measures designed to mitigate, soften, or divert the strike's force. Active includes denying entry of a person or substance or delivery system to the continent or states and our island territories, or access to sources of water, clean air, and crops; to large buildings, airports; and population-gathering centers. Passive includes rapid warning and evacuation, quarantining, mitigating through vaccines, health, and fire and police intervention.     

Parametric synthesis of passive filter-compensating devices

A method of optimal design for passive power filters based on performance optimization in the space of input impedance parameters is considered. The poles and the normalization coefficient of the filter operating impedance are variable parameters. A filter designed with the help of the proposed method satisfies requirements of reactive power compensation, harmonic filtering, and minimizing the amplification of minor harmonics. A design example illustrating the proposed approach is given.     

Silica-based planar lightwave circuits: passive and thermallyactive devices

Silica-based planar lightwave circuits (PLCs) are playing key roles in both optical dense wavelength-division multiplexing networks and optical access networks. This paper provides an outline of PLC technology focusing on passive devices such as arrayed waveguide grating multiplexers     

Magnetron sputter-deposited multilayer (BaxSr1x)Ti1+yO3+z thin films for passive and active devices

Abstract

High permittivity (Ba_xSr_1?x)Ti_1+yO_3+z(BST) thin films are being investigated for integration into charge storage dielectrics and electric-field tunable elements for high frequency devices. For the latter application, it is desirable to have BST capacitors with high tunability and low losses. Therefore, we investigated the use of multilayer BST thin films consisting of very low dielectric loss BST/electrode interfacial layers ((Ba+Sr)/Ti = 0.73) sandwiching a high tunability, high permittivity primary BST layer ((Ba+Sr)/Ti = 0.9). BST capacitors with multiple layers of controlled composition can be effectively produced insitu by magnetron sputter deposition, using a single stoichiometric target and controlling the layer composition by changing the total process gas (Ar+O<₂) pressure. The layered BST film capacitors exhibit simultaneous low loss (tan Δ = 0.005), high tunability (76%), high charge storage energy density (34 J/cm³), low leakage, and high dielectric breakdown (>2.8 MV/cm).     

Semiconductor arrayed waveguide gratings for photonic integrated devices

This paper reviews recent progress of the semiconductor arrayed waveguide gratings (AWGs) and the integrated semiconductor optical devices including the semiconductor AWGs. Recent research enables us to make semiconductor AWGs with sufficiently low insertion loss and polarization dependence. Using the semiconductor AWGs as core components, the integrated semiconductor optical devices are developing by integrating with the other semiconductor devices including photodetectors, optical amplifiers, and electroabsorption modulators.     

基于覆铜箔层压板的无源集成EMI滤波器设计

一种基于CCL交错并联的平面无源集成EMI滤波器结构,运用此结构可将共模电感,差模电感,共模电容集成为一个元件;相比传统EMI滤波器,集成的EMI滤波器实现了电容等效串联电感的最小化。给出了相关参数的计算,仿真集成EMI滤波器和传统EMI滤波器的共模插入损耗。最后制作了实验样机并得出了实验结果,验证了所提结构的正确性与可行性。     

Thermo-mechanical stress analysis for an integrated passive resonant module

In recent years, passive integrated power electronic modules (IPEMs), which have been implemented as resonant tanks in resonant dc-dc converters, have gained interest because of their merits for possibly reducing the total volume and improving manufacturability of the resonant converter system. However, the integration process for the passive IPEM increases the complexity of the thermal and mechanical behavior of the structure due to interactive heating of the module layers and mechanical inter-layer stresses. It is therefore essential to investigate the thermo-mechanical behavior of a passive IPEM to ensure reliable operation. In this paper, the methodology for thermo-mechanical analysis for a series resonant LC passive IPEM is developed. Especially, a three-dimensional thermo-mechanical model based on finite-element modeling is presented. The thermal analysis results were verified by an experimental prototype LC passive IPEM and temperature distribution measurement using an infrared camera and thermocouples. Results of the thermal analysis and the associated thermo-mechanical stress analysis are also discussed, illustrating the viability of the methodology developed for thermally induced mechanical stresses.     

Handheld devices with integrated MTI Micro fuel cell

NY-based MTI MicroFuel Cells has launched its Mobion? technology in the form of the world's first handheld entertainment system and PDA/smart phone powered by an integrated direct methanol fuel cell. Mobion represents a number of scientific breakthroughs that the company believes will ultimately enable it to power portable devices for 2–10 times longer than an equivalent-size battery pack, while allowing for instant, cord-free recharging.     

Sol-gel processed ferroelectric and multiferroic thin films for integrated devices

Abstract

Ferroelectric barium titanate and multiferroelectric bismuth ferrite thin films have been fabricated by using sol-gel processing technique. The starting materials for fabrication of were barium 2-ethyl hexanoate and titanium (IV) isoproposxide. Bismuth nitrate and ferric nitrate were the precursors for the fabrication of thin films. The as-deposited films were annealed at higher temperature for crystallization. The X-ray diffraction study on the films showed that the as-grown films were found to be amorphous that crystalized to proper phases by annealing at 550?°C in air for one hour. All the samples showed high optical transparencies in the visible frequency range. The room temperature dielectric constant and loss tangent of barium titanate thin films at 1?kHz frequency were found to be 400 and 0.01 respectively. Both the dielectric constant and loss tangent showed small dispersion in the frequency range of 0.10–1000?kHz range. The ferroelectricity in barium titanate thin films was confirmed by the presence of bell shaped capacitance-voltage (C-V) butterfly loop and saturated polarization-field (P-E) hysteresis loop. The as-grown bismuth ferrite thin films were also found to be amorphous that crystallizes after annealing at 500?°C. These films also showed high optical transparencies in the visible region. The bismuth ferrite thin film samples showed saturated hysteresis loop and magnetic polarization-magnetic field hysteresis loop as well, confirming the multiferroic nature of the samples.     

微波铁氧体器件现状及新一代集成化微波铁氧体器件展望

阐述了微波铁氧体器件发展现状,指出了微波铁氧体器件当前应该发展的技术方向和亟需突破的关键技术,强调微波铁氧体器件小型化和便于IC集成要求迫在眉睫。为实现微波铁氧体器件的小型化,从微波铁氧体器件基本原理入手,论述了圆极化概念在微波铁氧体器件功能实现和性能优化方面的重要作用,提出了采用绝缘多导体磁性结构实现可满足小型化和便于集成化要求的新一代微波铁氧体器件的基本思路。绝缘多导体磁性器件结构可实现多个TEM波模式的混合传输,利用此构造关于磁化偏置方向的正负圆极化波,从而产生显著的非互易传输和电控特性。TEM模式没有低频截止问题,器件尺寸可大体不受波长比拟规则的限制,通过目前日趋成熟的磁性集成化工艺,可实现小型化和便于IC集成化的新一代微波铁氧体器件。     

Simulation and design of integrated femtosecond passively mode-locked semiconductor ring lasers including integrated passive pulse shaping components

In this paper, a model is presented for the simulation of integrated passively mode-locked InP-InGaAsP ring laser systems that include active components such as an amplifier and saturable absorber, and passive components that can be frequency dispersive. These dispersive components can have a complex frequency dependence, such as arrayed waveguide gratings (AWGs). The model is a lumped-element model that is used as a design tool for developing integrated femtosecond pulse sources with internal dispersion control. Simulations based on an InP/InGaAsP amplifier and absorber show the possibility of laser designs that are able to generate pulses with pulse durations down to 300 fs in the 1550-nm wavelength range. The designs are based on femtosecond laser systems in bulk and fiber optics that are published in the literature. The femtosecond laser sources presented here can be realized using existing InP-InGaAsP active-passive integration technology.     

并联有源滤波装置选型方法

本文主要介绍并联有源滤波技术以及并联有源滤波装置的选型方法,重点阐述一种处于国际领先水平、适合于各行业的并联有源滤波装置的应用案例。     

适用于工业企业变电站的保护测控一体化装置开发

大型工业企业变电站对自动化产品的需求与日俱增,但与电力系统主电网中的变电站相比有其特殊性,借鉴成熟的电力系统变电站综合自动化技术和以太网通信技术,基于新型的MCU硬件平台和VxWorks嵌入式操作系统,开发了一套系列化的保护测控一体化装置,为实现企业变电站的自动化提供了先进的解决方案。针对目前企业变电站中应用的保护测控装置普遍存在的问题,提出了相应的解决方法,实践证明该装置能很好地适应工业企业变电站的特殊运行要求。     

含分布式供能设备的综合能源系统规划评价

综合能源系统作为能源领域发展趋势,对其进行综合评估,在规划阶段进行方案优选,保证最大化能源利用效率以及供能系统安全稳定运行,具有至关重要的意义。本文从可靠性、经济性、环保性角度出发,以热电联供系统为例,综合考虑电网、热网特性建立了综合能源系统评价体系。鉴于评价指标量纲不同以及指标优劣的模糊性,采用模糊综合评价法对指标进行模糊变换,通过反熵权法确定权重,针对不同的用户供能设备配置方案,将评价矩阵转换为综合评分。通过算例验证了本文所提评价体系的可行性和有效性,并给出了不同设备的配置建议。结果表明,小型燃气锅炉不宜在热电联供系统中进行配置,分布式光伏和电热水锅炉可显著提升系统性能,并且提升的幅度存在边际效应。     

适用于工业企业变电站的保护测控一体化装置开发

大型工业企业变电站对自动化产品的需求与日俱增,但与电力系统主电网中的变电站相比有其特殊性,借鉴成熟的电力系统变电站综合自动化技术和以太网通信技术,基于新型的MCU硬件平台和VxWorks嵌入式操作系统,开发了一套系列化的保护测控一体化装置,为实现企业变电站的自动化提供了先进的解决方案.针对目前企业变电站中应用的保护测控装置普遍存在的问题,提出了相应的解决方法,实践证明该装置能很好地适应工业企业变电站的特殊运行要求.