Propagation characteristics of magnetoelastic surface wave

The propagation characteristics of a magnetoelastic surface wave in ferrites are described using numerical calculations pertinent to gallium-y.i.g.     

Effects of surface metallisation on SSBW and BGW propagation in quartz

The letter describes theoretical results of the effects of surface metallisation on surface-skimming-bulk-wave (SSBW) and Bleustein-Gulyaev-wave (BGW) propagation characteristics for rotated Y-cuts of quartz. For a range of rotations, the surface metallisation increases the surface mechanical displacement of the BGW relative to the SSBW. The metallisation is ineffective in trapping the SSBW energy close to the surface.     

海浪谱的选择对海面电磁波散射建模的影响

海浪谱的选择对Bragg共振散射建模的影响是海面电磁波散射建模的关键问题。首先简介了海浪谱的概念,然后选择RA(Romeiser-Alpers)谱进行了Bragg共振散射建模,最后选择另一种具有代表性的PM(Pierson-Moskowitz)谱进行了Bragg共振散射建模,并通过仿真实验对两种海浪谱及其用于Bragg共振散射建模的效果进行了比较分析。获得的结论对合理地选择海浪谱具有指导意义。     

Numerical solution of the delay of a magnetoelastic wave

Numerical solutions for the delay of a zdirected magnetoelastic wave are compared with approximate solutions. It is found that the approximate solutions involve two errors that, in general, nearly cancel.     

参量变化对长程表面等离子体波特性的影响

为了掌握长程表面等离子体波的共振角度、共振峰半峰全宽以及衰减峰深度等重要特性,采用棱镜耦合激发介质-金属薄膜-介质对称结构中的长程表面等离子体波,研究了金属膜材料、厚度、介质折射率及介质厚度等参量变化时对长程表面等离子体波特性的影响。结果表明,实验中激发的长程表面等离子体波的衰减峰半峰全宽比传统的窄1~2个数量级;当介质膜厚度为500nm和1300nm时,激发的表面等离子体波的衰减深度只有薄膜厚度为700nm和1000nm时的1/2左右;随着介质膜厚度的增加,半峰全宽减小,金属膜越薄,衰减深度越深,衰减峰的半峰全宽值越小;介质膜折射率的改变对于半峰全宽的影响不明显;金属膜参量的变化将改变共振峰的位置。该研究为长程表面等离子体波的激发及应用于传感领域提供了有效依据,有利于其在波导和生物传感等方面的应用。     

Influence of the magnetoelastic effect on the microwave magnetic properties of Fe-N thin films

The microwave permeability of nitrogen-doped iron films deposited on a flexible lavsan substrate has been experimentally investigated. The measurements were performed with the use of a coaxial transmission line. The coaxial samples were coiled from a flexible film in two different ways: with the deposited layer facing outward and with the deposited layer facing inward. It has been found that the measured frequency dependences of the permeability of the two samples strongly differ. A comparison is made between the microwave permeabilities measured in the coaxial transmission line and in a strip transmission line, in which planar samples were used. It is shown that investigation of the influence of the magnetoelastic effect on the magnetic properties at microwave frequencies can provide additional information on the magnetic structure of the material.     

Laser activation and metallisation of oxide ceramics

UV excimer laser irradiation of oxides such as SrTiO₃, PbTi_{1 ? x}Zr_xO₃ (PZT) and Al₂O₃ results in the formation of colour centres. These colour centres mediate catalytic activity for electroless plating from Cu and Ni solutions. The adherence of the metal deposits to the as-sintered ceramic surfaces is excellent.     

Excitation of surface wave on circular-loop array

A method is presented of analyzing surface-wave excitation to an infinite periodic linear array in which only one element is excited and all others are parasitic. The approach taken in the analysis is based on the properties of the periodic structure. A formal solution for the current distribution on the array element is obtained, and the propagation constant of the surface wave is also found. In the case where the array consists of loop antennas, the surface wave can propagate only when the separation of the array element is less than one-half wavelength and the circumference of the loop is less than one wavelength. Calculated values of the propagation constant of an array are in good agreement with the measured results.     

Acoustic surface wave filters

Acoustic surface waves offer several advantages in the construction of delay lines and filters in the UHF range. In these devices the frequency response is determined by the finger spacing and overlap of the interdigital comb structures used as input and output transducers. Models are developed to describe these devices, and the predictions of these theories are compared with several experimental filters, including band-pass filters and dispersive delay lines.     

光栅辅助的表面波传感器研究

采用严格耦合波方法研究了普通棱镜耦合的表面波传感器与光栅辅助的表面波传感器的传感特性。设计了工作在1550nm处的一维光子晶体与光栅的材料参数与结构参数。光栅的深度为20nm,周期为524.6nm,占空比为0.5。模拟计算表明,光栅的引入导致双共振峰的出现,表面波的模式出现分裂。当外界折射率变化时,两个共振峰向相反的方向移动。利用双共振峰的这种特性进行传感,可以使光栅辅助的表面波传感器的角度灵敏度提高到普通棱镜结构的表面波传感器的3倍以上。     

Laser-Assisted etching and metallisation of via-holes in polyethylene terephthalate

Experimental results are presented on via-hole etching in a thick (100 μm) film of polyethylene terephthalate (PET) with the help of a copper vapour laser (wavelength γ=510 nm, pulse duration 10 ns, repetition rate 8 kHz). The rate of via-hole formation is as high as 100 μms^?1. The effective coupling of the polymer film to the laser radiation is due to the formation of highly absorbing graphitised regions in the bulk of the film, which is initially transparent at the laser wavelength. The side walls of the hole can be metallised by simultaneous decomposition of a Pd(acac)₂ spun-on layer as a precursor for subsequent electroless Ni deposition. The activation of the inner surface of the hole is achieved as a result of the precursor vapour entering the hole during laser etching. The metallised via-hole provides a good electrical interconnection of the two sides of the PET film.     

Magnetoelastic surface wave in ferrites

A magnetoelastic surface wave is shown to exist in an elastically isotropic ferrite, e.g. y.i.g. The wave exhibits a nonreciprocal behaviour, and is found to have no counterpart in a purely elastic medium.     

MEMS-IDT声表面波陀螺

声表面波陀螺的概念出现在70年代初期,发展为MEMS-IDT声表面波陀螺仅是最近几年的事情。MEMS-IDT声表面波陀螺仪是一种MEMS微机械振动陀螺,这种陀螺为单层平面结构,采用标准IC工艺就可完成加工,勿需悬浮的振动元件,有很强的抗冲击振动能力,可靠性高,可不用真空封装而保持较高的灵敏度。     

Practical surface acoustic wave devices

A tutorial discussion is presented on selected surface acoustic wave (SAW) devices for the use of engineers and electronic systems designers. Currently practical components for use in radar systems, communications systems, and as frequency domain filters are described. Emphasis is placed on nondispersive and dispersive delay lines, devices for generating and detecting various radar waveforms, devices for generating and detecting fixed and programmable biphase and multiphase codes, and broad-band and narrow-band filters. The device possibilities of several new approaches are described, including multistrip couplers, nonlinear convolvers, reflective structures, and overlay films. It is concluded that, while SAW devices have found many applications in large radar systems because of their size, cost effectiveness, and reliability, wide-scale applications, for example as frequency domain filters, will be needed to justify continued research in this field. Wide-scale applications will come as systems engineers realize the potential of these devices and confidently design them into their systems.     

Magnetostatic surface wave straight-edge resonators

The performance of the magnetostatic surface wave straight-edge resonator (MSSW-SER) is presented. The resonator uses a rectangular YIG film to propagate MSSWs where the straight edge serves as a reflector. Problems arising from coupling to width mode resonances and their effect on the main resonance are investigated. Through a careful choice of YIG and transducer parameters, the interference effects of the width mode resonances with the main resonance are minimized. As a result, highQ tunable microwave resonators with a tuning range from 2–20 GHz, insertion loss less than 10 dB, and spurious rejection better than 10 dB could be designed and fabricated. This MSSW resonator could be used to construct a tunable low-phase-noise feedback oscillator. However, the tuning range of this MSW feedback oscillator is limited by the phase change of the external amplifier circuit.     

基于石墨烯的布洛赫表面波调控特性研究

布洛赫表面波(Bloch surface wave,BSW) 具有传输损耗低、显著表面局域场增强、环境敏感等特性,因而被视为研究近场光和物质相互作用的关键技术。其主要在截断的一维光子晶体与外界介质的界面激发并沿此界面传播,通过传播界面微纳结构的设计,可在纳米尺度实现对BSW的有效调控。本文从BSW的模式特性出发,提出了石墨烯加载的一维光子晶体BSW传感器件结构。通过改变石墨烯层的结构参数,调节激发模式在光子带隙中的位置,研究激发模式的光场传输特性,实现对BSW激发波长、振幅和相位的调控。进一步利用其对外界介质折射率变化非常敏感的特性,对其传感检测能力进行研究。结果表明,该器件有望实现高灵敏度的生化传感检测应用。该研究为新型BSW集成光子器件的设计与发展提供了新思路。     

Evolution of metal plating for silicon solar cell metallisation

Increasing silver prices and reducing silicon wafer thicknesses provide incentives for silicon solar cell manufacturing to develop new metallisation strategies that do not rely on screen printing and preferably reduce silver usage. Recently, metal plating has re‐emerged as a metallisation process that may address these future requirements. This paper reports on the evolution of metal plating techniques, from their use in early silicon solar cells, to current light‐induced plating processes. Unlike screen‐printed metallisation, metal plating typically requires an initial patterning step to create openings in a masking layer for the subsequent self‐aligned metallisation. Consequently, relevant recently‐developed dielectric patterning methods are also reviewed because, in many cases, the plating process must be adapted to the properties of the patterning method used. The potential of new light‐induced plating processes to form cost‐effective copper metallisation is supported by the recent activity in the development of metal plating tools for commercial silicon solar cell manufacture. Copyright © 2012 John Wiley & Sons, Ltd.     

Frequency-selective scanning of acoustic surface wave

An acoustic-surface-wave point source is obtained when an interdigital transducer with concentric curved fingers is used. An array transducer composed of 80 point sources has been tested. The direction of propagation of the surface-wave beam emitted by this transducer depends on the frequency. A transmitting-array transducer and five receiving transducers are deposited on a quartz substrate. Each of these five outputs corresponds to a given frequency and delay prescribed by the positioning. At 12°, scanning was attained for a frequency variation of 7.6 MHz around a central frequency of about 60 MHz, corresponding to a delay variation of 18.2 ?s.     

基于小波分解表面波的涂层平板表面缺陷检测方法研究

激光照射在涂层平板表面产生的超声表面波传播时会产生色散现象,该现象会影响表面缺陷检测精度.针对表面波的色散问题,采用有限元仿真分析表面波在涂层平板表面的传播规律,利用Morse小波分解多频表面波信号,提取最大幅值单一频率的缺陷时域信号从而确定表面缺陷位置.在此基础上通过扫描缺陷附近检测点的方式,分析缺陷前沿入射波和缺陷...