Planar waveguide optical spectrum analyzer using a UV-inducedgrating

An optical spectrum analyzer is demonstrated using a UV-induced, chirped grating on a planar waveguide and a linear detector array. The grating provides both the dispersion with respect to wavelength and the imaging function. The spectral response has a full-width at half-maximum of 0.15 nm and a bandwidth of 7.8 nm. A chirp of -1.75 nm/cm and a 12-cm focal length were used. The design parameters are discussed in terms of the chirp, focal length and resolution. The wavelength dependence of the optimal chirp limits the resolution for small focal lengths. For longer focal lengths, the spotsize is diffraction limited and high resolution can be achieved with minimal fabrication complexity     

Design of tapered SAW waveguide for wavelength‐selective optical switches using weighted acoustooptic interaction

Optical wavelength‐selectivity in optical switches using waveguide‐type collinear acoustooptic interaction is studied from the viewpoint of sidelobe suppression. It is found that the sidelobe level can be reduced from ?9.3 dB to ?20 dB by weighting the coupling coefficient over the interaction region. A method to realize the sidelobe suppression by means of modifying the surface acoustic wave (SAW) waveguide is proposed and theoretically analyzed to design the SAW waveguide. A sidelobe suppression at ?20 dB is realized with a SAW waveguide of a dense‐flint glass strip whose width and thickness are varied accordingly in the ranges of 700 to 26 µm, and 0.4 to 1.0 µm, respectively, on a Y‐X LiNbO₃ substrate. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(1): 36–46, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20251     

Optical memristive switches

Optical memristive switches are particularly interesting for the use as latching optical switches, as a novel optical memory or as a digital optical switch. The optical memristive effect has recently enabled a miniaturization of optical devices far beyond of what seemed feasible. The smallest optical – or plasmonic – switch has now atomic scale and in fact is switched by moving single atoms. In this review, we summarize the development of optical memristive switches on their path from the micro- to the atomic scale. Three memristive effects that are important to the optical field are discussed in more detail. Among them are the phase transition effect, the valency change effect and the electrochemical metallization.     

Composite resonant switches

Main types of zero-current and zero-voltage composite resonant switches are described. Their basic properties and characteristics are analyzed. It is shown that the use of these switches ensures soft switching conditions for all switching elements of the circuit, including the primary, antiphase, and auxiliary ones.     

Multifunctional integrated photonic switches

Traditional optical-electronic-optical (o-e-o) conversion in today's optical networks requires cascading separately packaged electronic and optoelectronic chips and propagating high-speed electrical signals through and between these discrete modules. This increases the packaging and component costs, size, power consumption, and heat dissipation. As a remedy, we introduce a novel, chip-scale photonic switching architecture that operates by confining high-speed electrical signals in a compact optoelectronic chip and provides multiple network functions on such a single chip. This new technology features low optical and electrical power consumption, small installation space, high-speed operation, two-dimensional scalability, and remote electrical configurability. We present both theoretical and experimental discussion of our monolithically integrated photonic switches that incorporate quantum-well waveguide modulators directly driven by on-chip surface-illuminated photodetectors. These switches can be conveniently arrayed two-dimensionally on a single chip to realize a number of network functions. Of those, we have experimentally demonstrated arbitrary wavelength conversion across 45 nm and dual-wavelength broadcasting over 20 nm, both spanning the telecommunication center band (1530-1565 nm) at switching speeds up to 2.5 Gb/s. Our theoretical calculations predict the capability of achieving optical switching at rates in excess of 10 Gb/s using milliwatt-level optical and electrical switching powers.     

Semiconductor optical space switches

This paper reviews the various optical space switch structures on III-V semiconductor material. Their characteristics are discussed in the context of optical transport and switching network applications exploiting wavelength division multiplexing     

Planar antennas

This article reviews the state of the art in broadband antennas for emerging UWB applications and addresses the important issues of the broadband antenna design for UWB applications. First, a variety of planar monopoles with finite ground planes are reviewed. Next, the roll antennas with enhanced radiation performance are outlined. After that, the planar antennas printed on PCBs are described. A directional antipodal Vivaldi antenna is also presented for UWB applications. Last, a UWB antenna for wearable applications is exemplified     

Resonant snubbers with auxiliary switches

A resonant snubber is described for voltage-source inverters, current-source inverters, and self-commutated frequency changers. The main self-turnoff devices have shunt capacitors directly across them. A temporary parallel path through a small ordinary thyristor and inductance takes over high-stress turn-on duty from the main device in a manner that leaves no energy trapped after switching     

RF MEMS switches and switch circuits

MEMS switches are devices that use mechanical movement to achieve a short circuit or an open circuit in the RF transmission line. RF MEMS switches are the specific micromechanical switches that are designed to operate at RF-to-millimeter-wave frequencies (0.1 to 100 GHz). The forces required for the mechanical movement can be obtained using electrostatic, magnetostatic, piezoelectric, or thermal designs. To date, only electrostatic-type switches have been demonstrated at 0.1-100 GHz with high reliability (100 million to 10 billion cycles) and wafer-scale manufacturing techniques. It is for this reason that this article will concentrate on electrostatic switches     

Switching operations of three-waveguide optical switches

Three-waveguide optical switches are analyzed by means of the coupled mode theory. Assuming that three approximate waveguides of an optical switch are identical and equally spaced, we examine the switching behavior for cases where an incident beam is launched into (1) an outer waveguide and into (2) a center waveguide. For each beam-launching case, switching voltage is applied so that the overall index profile is detuned (1) symmetrically or (2) antisymmetrically. It is concluded that only three types of optical switches out of these four configurations can perform the switching operation. We derive the switching conditions for each of three possible types and draw the corresponding switching diagrams     

单片开关电源

单片开关电源的主要特点 TOPSwitch-Ⅱ系列产品包括TOP221P/G～TOP224P/G和TOP221Y～TOP227Y。该系列产品具有以下显著特点: (1)将脉宽调制(PWM)控制系统的全部功能集成到三端芯片中,内含脉宽调制器、功率开关场效应管(MOSFET)、自动偏置电路、保护电路、高压起动电路和环路补偿电路,通过高频变压器使输出端与电网完全隔离,     

无开关灭磁实用技术

发电机在正常和事故停机时,一般利用灭磁开关来消耗转子中剩余的能量。但这种传统的灭磁方式不仅使励磁系统的结构过于复杂,也增加了系统设备的运行维护成本。无开关灭磁技术根据发电机组不同运行工况下可能产生的转子过电压情况,结合逆变灭磁,并利用跨接器可快速开断的优点,合理设计控制策略,满足发电机安全、可靠的灭磁要求。     

DC-DC开关电源模块并联供电系统

为设计一种DC-DC开关电源并联供电系统,采用DC-DC主从模式实现两个开关电源的并联供电,并按比例自动分配电流。设计采用STC12C5A60S2单片机完成A/D采集主从模块及其总电流,再通过D/A控制从模块的电流,以实现主从模块按比例输出电流供给负载。DC-DC主从模块是由开关电源控制芯片SG3525为核心完成PWM产生,BUCK拓扑结构和反馈电路组成。这个系统实现可手动或自动调节电源比例的并联稳压供电,最大输出可达到4 A-8 V直流,效率高达83%。介绍了系统结构、DC-DC主从模块、测量电路、系统供电以及主控机原理,详细介绍系统结构、DC-DC主模块和主控电路。     

Fault macromodel for switches in switched-current circuits

Based on possible defects on the layout of a practical non-ideal switch, fault model and test generation of current copiers, basic building block of switched-current circuits, are presented in this study, where we consider two types of switches, current switches and voltage switches, which have been commonly used in both switched-current circuits and switched-capacitor circuits. Both catastrophic and parametric faults of transistors used as switches are considered. Test sequences are proposed to achieve full testability of both current copiers and switched-current circuits. © 1998 John Wiley & Sons, Ltd.     

配电系统联络开关的优化配置

将联络开关优化配置的目标设为以提高系统可靠性原则为前提,寻求使网络重构得到的系统网损最小的配置方案.提出了两个启发式准则,即根据联络开关的分类和待联接联络开关的端点的电压差来指导联络开关的优化配置,并采用一种新的高效并行的可处理大规模三相不平衡配电系统的网络重构算法来保证获得网络重构的优化结果.算例表明该启发式算法对三相平衡和不平衡系统都是快捷和有效的.     

Off-plane computer-generated waveguide hologram

We present the theory, design, fabrication and evaluation of off-plane computer-generated waveguide holograms (OP-CGWHs). The hologram structure is composed of an array of rectangular elements each containing a waveguide grating coupler. The function of the rectangular elements is twofold: outcoupling the guided optical wave, and introducing phase shift. The phase shift of each rectangular element can be determined by controlling the dislocation of the grating grooves along the guided wave propagation direction. In addition, the phase pattern of the OP-CGWH can be designed using many existing algorithms for computer-generated holograms (CGH), such as the iterative Fourier transform algorithm (IFTA). A design example is presented for a waveguide array generator, which outcouples a Gaussian-like incident guided wave and simultaneously produces an array of spots in free space. Such an OP-CGWH device, based on an AlGaAs-GaAs waveguide, was fabricated using electron-beam lithography and reactive ion beam etching. Experimental results are presented that demonstrate the effectiveness of the proposed idea. The uniformity error and the power efficiency of the fabricated OP-CGWH array generator were measured to be approximately 8% and 30%, respectively     

Resonant switches: Basic types and application

Basic types of resonant switches with zero voltage and zero current switching are presented. Their main properties and characteristics are considered. Application of all types of resonant switches with the frequency and pulse-width control is shown.