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Two-dimensional real time imaging of the propagation of surface waves on materials in picosecond temporal regime

皮秒时间范围内表面波在材料上传播的二维实时成像

基本信息

批准号：
14205014
负责人：
MATSUDA Osamu
金额：
$ 35.36万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Imaging of the surface acoustic phonon focusing phenomena reveals complicated patterns of the acoustic energy propagation in anisotropic materials. The imaging technique is expected to play an important role in the development of surface acoustic wave devices in GHz frequency region. In this study, we develop a real-time two-dimensional imaging technique for the surface acoustic wave propagation. It is based on the ultrafast optical pump-probe method and the extremely stable common-path optical interferometer. In case of the diamond substrate covered with Au film, it is shown that the surface acoustic phonon up to 2 GHz is generated and detected by this method. We also develop the analysis method to obtain the multiple mode of the surface acoustic phonon directly from the experimental results on transparent and opaque, isotropic and anisotropic samples.As a new imaging technique especially for opaque samples, a method using automated mirror is developed. As for the detection of the surface acoustic wave, instead of the interferometer, the method based on the reflectivity change is developed. In relation to this, we develop the light scattering theory that is applicable to the normal and non-normal probe light incidence to the anistropic multilayer sample with inhomogeneous optical properties.As an application of the technique, the surface acoustic wave is imaged in the poly-crystalline Cu sample consists of micron size grains. The diffraction and reflection at the grain boundary is clearly observed. The result is compared with the simulation based on the FDTD method. It provides the opportunity to evaluate the subsurface structure around the grain boundaries.In summary, we have developed the general purpose surface acoustic wave measurement and analysis method with pico-second time resolution and micron scale spatial resolutions. By this method, we have clarified the physics of surface acoustic wave propagation in MHz-GHz frequency region.

表面声学声子聚焦现象的成像揭示了各向异性材料中声能传播的复杂模式。这种成像技术有望在GHz频段声表面波器件的发展中发挥重要作用。在这项研究中，我们开发了一种实时二维成像技术的表面声波传播。它基于超快光学泵浦探测方法和极其稳定的共光路光学干涉仪。在金刚石衬底上覆盖有Au薄膜的情况下，它表明，表面声学声子高达2 GHz的产生和检测由这种方法。我们还发展了直接从透明和不透明样品、各向同性和各向异性样品的实验结果中获得表面声学声子多模态的分析方法。对于声表面波的检测，本文提出了一种基于反射率变化的声表面波检测方法。在此基础上，我们建立了适用于探测光垂直和非垂直入射到具有非均匀光学性质的各向异性多层膜样品的光散射理论，并应用该理论对由微米级晶粒组成的多晶Cu样品进行了声表面波成像。晶界处的衍射和反射现象清晰可见。并与基于FDTD方法的仿真结果进行了比较。总之，我们已经开发了具有皮秒级时间分辨率和微米级空间分辨率的通用表面声波测量和分析方法。用这种方法，我们阐明了声表面波在MHz-GHz频段的传播物理。