声光器件的换能器带宽和镀层厚度的确定

本文将综述以Mason等效电路为基础的计算声光器件中压电换能器频率响应的理论,它对于声光器件中换能器的设计和性能测试是极重要的.本文将应用此理论对目前最重要的两种声光器件(36°Y切LN/PM和X切LN/TeO_2)以及各种镀层材料和厚度计算换能器捐耗TL随相对频率f/f_0的变化关系,由此可确定各镀层的厚度和器件的换能器带宽.本文还给出这两种器件的电输入阻抗Z_1在阻抗园图上随f/f_0变化的轨迹,它可作为器件性能测试的理论依据.     

氯化亚汞声光器件三层换能器的优化设计

提出用环氧树脂聚合物作为缓冲层，设计氯化亚汞声光器件的换能器。从器件的布喇格带宽和工艺条件出发，优化设计了三层（含顶电极，缓冲层，底电极）结构的换能器，计算了以不同金属材料为电极时，其三层的各自厚度，并确保了换能器的倍频程带宽。     

用于光纤声光器件的超声换能器与模式转换器

研制了一种可用于全光纤声光器件的超声换能器,设计了由光纤和换能器构成的纵-弯模式转换系统,并将所作的换能器和模式转换系统应用于光纤声光可变衰减实验。结果表明,设计的换能器既有较宽带宽又有较高发射效率,完全可以满足全光纤声光器件的需要。     

声光器件

近年来,随着激光技术的发展,以激光为中心对光束进行时间的或空间的控制(调制)已发展成一个重要的技术领域.对光束的调制,有直接调制光源(半导体激光等)的驱动电流等内部调制法和下面将介绍的外部调制法.而外部调制法又可大致分为:(1)机械法;(2)电光法;(3)磁光法;(4)声光法(表1).其中广泛使用的是机械法和声光法.     

Hg2Br2声光器件的换能器电输入阻抗特性

利用压电换能器等效电路网络分析法，以环氧树脂为缓冲层(粘接层)的X-切LN／Hg2Br2声光器件计算了换能器的规一化电输入阻抗|Z1|随规一化频率f／f0，的变化关系，绘出了|Zi|-f／f0关系立体图，得出器件的输入阻抗是射频频率复杂的复数函数及在不同频率段分别呈现感抗和容抗的特性，给出了器件的规一化输入阻抗|Zi|在阻抗Smith圆图上随，f／f0变化的轨迹，作为器件性能测试的理论依据。     

Hg_2Br_2声光器件的换能器电输入阻抗特性

利用压电换能器等效电路网络分析法,以环氧树脂为缓冲层(粘接层)的X-切LN/Hg2Br2声光器件计算了换能器的规一化电输入阻抗|Zi|随规一化频率f/f0,的变化关系,绘出了|Zi|-f/f0关系立体图。得出器件的输入阻抗是射频频率复杂的复数函数及在不同频率段分别呈现感抗和容抗的特性。给出了器件的规一化输入阻抗|Zi|在阻抗Smith圆图上随f/f0变化的轨迹,作为器件性能测试的理论依据。     

掠面体波器件

本文介绍一种潜在用途广泛的新型平面声波器件——掠面体波(SSBW)或浅体声波(SBAW)器件.对SSBW的基本性质,以及器件工作原理和优点等作了简单的叙述.     

在集成光学声光器件中表面声波相速的测定

基于共线声光耦合测定了质子交换的ＬｉＮｂＯ３波导中的表面声波的相速，该测量方法简便。准确，精度达１×１０－３，稍加变动可推广到非质子交换的其他波导的情形。     

用叉指换能器制作高频声体波换能器的理论研究

从理论上介绍一种利用叉指换能器制作高频声体波换能器的方法，具有结构和工艺简单，声波模式纯度较高，换能损耗较小和容易消除各种反射波影响的特点。     

多层体波换能器的变迹法

最近实验已证明,采用超晶格换能器可制作GHz频段的体声波器件.这种换能器是由多层交替结晶取向排列的ZnO或极化的LiNbO_3组成.讨论了每层由各向异性和压电性以及具有任意晶体取向组成的整个多层换能器的机电特性计算过程.这种算法是在具有商业程序的专用计算机上进行,这个系统数字稳定而且容易执行.也讨论了提供近似分析多层换能器特性和观察综合过程的网络模型.比较了两种计算方法并说明了宽带换能器的最初设计程序.     

Pyroelectric imaging of defects in bulk acoustic wave lithium niobate transducers

Initial results on a method for testing piezoelectric transducers made of a polar material are presented. The method consists of measuring the voltage induced across the transducer electrodes by an intensity-modulated laser beam scanning the surface. Applied to a bulk acoustic wave LiNbO3 transducer, this technique has revealed domains with Z-axis reversed.     

Radio frequency wave applications in magnetic fusion devices

An overview of RF wave applications in magnetic fusion devices is given. A summary of the wave physics, the present experimental progress, and the technological development of RF heating is presented. Particular emphasis is placed on the technological requirements of wave launchers, transmission systems, and RF generators for the three main frequency ranges: the ion cyclotron (ICRF), the lower hybrid (LHRF), and the electron cyclotron (ECRF). Some possible extrapolations of the present technology to CTR regimes are discussed.     

Integrated approach to electrode and AlN depositions for bulk acoustic wave (BAW) devices

This paper investigates the (002) texture of AlN films deposited by reactive pulsed direct current sputtering on Al, Al–Cu, W and Mo metal electrodes. X-Ray diffraction and atomic force microscopy studies show that the AlN texture is dependent on the deposition conditions and nature of the underlayers. A smooth underlayer with a sharp texture represents the best combination of properties. AlN films with a full width at half maximum less than 1.5 have been deposited on the electrodes studied. It is also possible to deposit well-textured electrodes with a roughness less than 2.5 nm.     

一种射频体声波滤波器的版图设计与仿真

射频体声波滤波器品质因子高,尺寸小,其性能已超过声表面波滤波器,将其替代传统的射频滤波器极具性能和价格优势。本文建立了适用于体声波滤波器性能分析的巴特沃斯—范戴克（MBVD）模型,采用梯形级联方式设计了一种射频体声波滤波器的版图。在此基础上以中心频率为1.99GHz,带宽56MHz的体声波滤波器为例,对不同连接级数梯形滤波器的插入损耗、阻带抑制进行了仿真与分析讨论,在4阶滤波器中其带外衰减达到了-29.708dB。采用微机电机械系统工艺制备的2阶和3阶滤波器传输特性的测试曲线与仿真结果基本吻合,表明射频体声波滤波器具有广泛的应用前景。该模拟结果可作为射频体声波滤波器设计的一个重要参考。     

Test method of frequency response based on diamond surface acoustic wave devices

In order to reduce the noises affixed to the signals when testing high frequency devices,a single-port test mode(S11) is used to test frequency response of high frequency(GHz) and dual-port surface acoustic wave devices(SAWDs) in this paper.The feasibility of the test is proved by simulating the Fabry-perot model.The frequency response of the high-frequency dual-port resonant-type diamond SAWD is measured by S11 and the dual-port test mode(S21),respectively.The results show that the quality factor of the device is 51.29 and the 3 dB bandwidth is 27.8 MHz by S11-mode measurement,which is better than the S21 mode,and is consistent with the frequency response curve by simulation.     

New family of bulk-acoustic-wave devices employing interdigital transducers

An important new family of acoustic wave devices is described which has the simplicity, versatility and planar construction of s.a.w. devices, together with the attractive properties of bulk-wave devices, including high velocity, low attenuation, good temperature stability and insensitivity to surface contamination.     

Schottky-gate bulk effect digital devices

Using the n-GaAs planar device with a Schottky barrier gate, a high-field dipole domain could be triggered from the high-field region under the Schottky gate by applying a negative pulse to the gate. The figure of trigger capability was obtained to be 24 mA/V for the sample used in experiments, and is possible to get up to 150 mA/V for a suitably designed device. Some fundamental experiments including a pulse regenerator were performed.     

Fiber attachment for guided wave devices

Reviews the status of fiber attachment to guided wave devices. Current methods for achieving low fiber-waveguide-fiber insertion loss are discussed and techniques for aligning and permanently attaching fibers are described     

频率特性测试仪

以集成的直接数字合成器(DDS)AD9851为核心,利用现场可编程门阵列(FPGA)及外围测量电路,设计并实现了一个频率特性测试仪,可用于测试某一特定网络的频率特性.并给出了幅频和相频特性曲线,并采用软件修正方法提高了整个系统输出的稳定性和可靠性.