Analysis of metal grating polarizers for quasi-optical power combining applications

Reflection and transmission characteristics of thin metal strip grating polarizers on dielectric substrate for quasi-optical power combining applications are analyzed by spectral domain method. Based on the calculated results, simple equivalent circuit models and empirical formula for analyzing metal grating polarizers are presented. The agreement between these simple expressions and spectral domain method are within one percent.     

Electromagnetic emission from two-dimensional plasmons in a semiconductor-dielectric structure with metal grating: Rigorous theory

The spectrum of electromagnetic (EM) radiation from two-dimensional(2D) plasmons in a semiconductor-dielectric structure with metal grating has been calculated in a strict electromagnetic approach. It is shown that radiation frequency and linewidth vary over a broad range of magnitude as a function of the grating parameters. The radiative decay linewidth is found to be two orders of magnitude larger than expected from the perturbation theory. Comparison of the results with previously published experimental data on 2D plasmons in GaAs heterostructures makes us conclude that the main contribution to the experimental decay linewidth arises from dielectric losses in the layers of the structure.     

Analysis of the scattering and guidance of a two-dimensionally periodic metal grating structure by spectral domain method

The scattering and guidance of electromagnetic waves from a two-dimensionally (2D) periodic metal grating structure are investigated here. With the spectral domain analysis the dispersion characteristics for this structure are obtained. Properly taking into account the hybrid mode nature of the propagation problem the effects of mode coupling betweenTE andTM modes are examined. Numerical results will provide us valuable information for the design of new devices in 2D periodic structure, particularly in millimeter-wave frequency range, such as antennas, filters, couplers and distributed reflectors.     

Surface-acoustic-wave propagation on a piezoelectric substrate with a periodic metal grating

An analysis is presented for modes propagating via a periodic metal grating on the surface of a piezoelectric substrate. Assuming no loss in the structure, the numerical solution is exact in the limit, combining the effective permittivity function formulation with the least-squares residual applied at the surface.     

Investigation of diode geometry and metal line pattern for robust ESD protection applications

The effect of different diode geometries and metal patterns on the failure current It2 is investigated experimentally. The devices considered are N+/P well LOCOS diodes having different lengths, widths, finger numbers, and metal connections. The results provide useful insights into optimizing the diode for robust electrostatic discharge (ESD) protection applications.     

双金属结构对布拉格光栅的温度补偿研究

本文首先提出了一些温度补偿的典型方法,然后设计了一个能够对布拉格光纤光栅实现温度补偿的双金属结构,并进行了研究.最后,双金属结构的布拉格光栅的温度特性在-5～ 50 ℃的温度范围内做了测试,实验结果表明,双金属结构的布拉格光栅的温度系数减小了4倍.     

光纤光栅保护增敏及光纤智能金属结构研究现状

从光纤光栅传感器传感原理出发,分析了波长漂移的影响因素,对光纤光栅增敏及封装保护现状进行了系统总结,指出了其中存在的不足和发展方向及应用前景.对光纤智能结构和智能金属结构的特点及应用情况进行了系统综述,分析了研究中存在的问题及应用前景.     

面向智能车辆应用的智能仿真车研究与设计

针对面向智能车辆研究的智能车仿真平台的构建问题,设计了一种智能仿真车,在研究智能车仿真平台基本结构的基础上,详细阐述了智能仿真车的软硬件设计;提出了一种基于霍夫变换的车道线识别方法,首先采用霍夫变换对车道线进行检测,之后使用多示例学习对车道线进行跟踪。实际应用表明,该智能仿真车能够满足相关技术的研究需求,具备良好的有效性和稳定性。     

114-nm wavelength tuning range of a vertical grating assistedcodirectional coupler laser with a super structure grating distributedBragg reflector

A vertical grating assisted codirectional coupler laser with a super structure grating distributed Bragg reflector is demonstrated. A record stepwise tuning range of 114 nm was measured with good side-mode suppression. The tuning behavior of the device is investigated showing a potential of a tuning range exceeding 100 nm with complete wavelength coverage     

Synthesis of the antenna pattern for a radiating slot in a metal cylinder

The synthesis of a prescribed far-field pattern by means of a radiating slot in a perfectly conducting infinite circular cylinder is considered. The narrow circumferential slot and the infinite axial slot are studied in detail. In either case, the problem is to find the distribution of the electromagnetic field in the aperture that yields a radiation pattern that is the best mean-square approximation to a given pattern, under certain constraints. Various quality factors for cylindrical modes are discussed, and a detailed comparison with the synthesis problem for a planar aperture is performed. It turns out that Rhodes' synthesis method has no equivalent in the cylindrical case, and that the best admissible mean-square approximation to a given pattern may be a very poor approximation in amplitude. However, an iteration scheme is developed in which the phase approximation is sacrificed for the sake of substantially improving the amplitude approximation. Numerical results based on such a scheme are displayed, for prescribed omnidirectional and sectoral patterns.     

ROADM技术的应用分析与新型设备形态的构想

随着光传送网(OTN)的广泛商用,可重构型光分插复用器(ROADM)技术逐渐成为OTN的重要光节点技术.文章分析了ROADM的3种主要技术,并针对不同的网络用途给出了选用建议.最后提出一种复合型ROADM设备形态,该设备形态结合了波长阻断器和波长选择开关型ROADM技术的优点,具有更强的适用性.     

面向车辆盲区防撞系统的交通目标智能检测

交通目标智能检测是车辆盲区智能防撞系统中的基础技术,该技术的研究和应用对降低交通事故损失具有重要意义.本文面向车辆盲区防撞系统设计的交通目标智能检测,其在基础模型中融合了两个性能提升策略.将该模型应用于国内和国外道路场景检测数据集,以验证模型在所有范围和近距离目标的检测性能.实验结果表明该模型可以对近距目标表现出较高的...     

Phase-sensitive interrogation of fiber Bragg grating resonators for sensing applications

This paper discusses a phase-sensitive technique for remote interrogation of passive Bragg grating Fabry-Pe/spl acute/rot resonators. It is based on Pound-Drever-Hall (PDH) laser frequency locking, using radio-frequency phase modulation sidebands to derive an error signal from the complex optical response, near resonance, of a Fabry-Pe/spl acute/rot interferometer. We examine how modulation frequency and resonance bandwidth affect this error signal. Experimental results are presented that demonstrate, when the laser is locked, this method detects differential phase shifts in the optical carrier relative to its sidebands, due to minute fiber optical path displacements.     

Design of a microstrip diplexer with a novel structure for WiMAX and wireless applications

In this paper, a novel combination of coupled lines, loops, step impedance and low impedance sections are used to design a compact microstrip diplexer. The designing method is based on obtaining transmission matrices and finding the effective parameters in tuning the resonance frequencies. T-shape tapped lines feed structures are added to three terminals of the proposed diplexer to decrease insertion losses at the both passbands without increasing the overall size. The proposed diplexer with a total size of 573.11 mm² operates at 2.6 GHz for IEEE 802.16 and 802.20 WiMAX technology and 6 GHz for wireless applications. The insertion losses at the lower and higher resonance frequencies are 0.6 dB and 0.9 dB, respectively. The proposed structure is simulated, fabricated and measured. The measurement results are in a good agreement with the simulations.     

Novel applications of fiber bragg grating components for next-generation WDM systems

The main purpose of this paper is to present an overview of novel applications enabled by major improvements realized in FBG technology. First, we will review the principle of operation of FBG-based components and the numerous recording techniques used to fabricate those types of components. We will next show that this technology combined with new innovative manufacturing process is well suited to overcome the challenges imposed on optical components for next-generation WDM systems.     

Development of a hybrid flywheel/battery drive system for electric vehicle applications

Today's electric vehicles are severely limited in multistop and go driving range and accelerating capability by the lead acid battery's inability to handle high power peaks while maintaining maximum energy storage capability. A hybrid flywheel/battery system can be used to isolate the battery from the accelerating power peaks, and should recover a substantial part of the braking energy. This paper describes the development of a small, high speed, lightweight flywheel/ ac synchronous motor alternator sealed energy storage package coupled into the battery and dc drive motor system through a simple rectifier/inverter power circuit. This system stores just enough energy in the rotor of the machine for one start-stop cycle. Provision is made to add a flywheel to store energy for several cycles, or enough energy for climbing or descending long grades. The fields of the two machines are electronically controlled to achieve optimum performance and effective energy utilization.     

Millimeter wave backscatter measurements in support of collision avoidance applications

Millimeter-wave short range radar systems have unique advantages in surface navigation applications, such as military vehicle mobility, aircraft landing assistance, and automotive collision avoidance. In collision avoidance applications, characterization of clutter due to terrain and roadside objects is necessary in order to maximize the signal-to-clutter ratio (SCR) and to minimize false alarms. The results of two types of radar cross section (RCS) measurements at 95 GHz are reported in this paper. The first set of measurements presents data on the normalized RCS (NRCS) as well as clutter distributions of various terrain types at low grazing angles of 5° and 7.5°. The second set of measurements presents RCS data and statistics on various types of roadside objects, such as metallic and wooden sign posts. These results are expected to be useful for designers of short-range millimeter-wave collision avoidance radar systems.     

量子阱红外探测器双面金属光栅设计优化

提出了一种增强量子阱红外探测器耦合效率的双面金属光栅结构。采用三维时域有限差分算法（3D-FDTD）对GaAs/AlGaAs 量子阱红外探测器双面结构金属光栅进行了仿真分析。通过对比不同周期、占空比、金属层厚度结构参数下探测器的电场分布及相对耦合效率,确定了4.8 m 探测器优化的双面金属光栅结构。与顶部和底部单层金属光栅结构比较,双面金属光栅结构探测器相对耦合效率提高到3 倍以上。探测器相对耦合效率随光栅周期变化的双峰曲线特性体现了双面金属光栅结构在双色量子阱红外探测器光耦合方面的潜力。同时该结构还可以应用于单色、双色及多色量子阱焦平面红外探测器。     

传感用光纤光栅写入技术的研究和发展

为克服目前传感应用领域借用传感性能并不优异的通信用光纤光栅的不足,在总结传感用光纤光栅制作技术的特点和要求基础上,对近年来传感用光纤光栅的制作技术进行了系统回顾,具体分析了耐高温、高机械强度、增敏/去敏等常见传感用布喇格光纤光栅的写入技术以及紫外曝光、机械变形、红外激光逐点写入等传感用长周期光纤光栅的制作方法,最后对传感用光纤光栅制作技术的发展方向进行了预测。