Optical Heterodyne Spectroscopy of Light Scattering by Laser Induced Phonons

激光诱导声子光散射的光学外差光谱

基本信息

批准号：
63460062
负责人：
TAKAGI Kenshiro
金额：
$ 4.74万
依托单位：
Institute of Industrial Science, Univ. of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

The fundamental requirement in the ultrasonic spectroscopy is to observe the velocity and absorption over extensive frequency range. In the last few years, we have developed various experimental techniques, including planoconcave ultrasonic resonator and high resolution Bragg reflection (to be referred as HRB) method. The purpose of this research project is to establish a new technique which is useful for the measurement of phonon velocity and decay at hypersonic range. For this purpose, we took advantage of the light beating spectroscopy to detect the light scattering by the thermal phonons. The success of the HRB method has shown that the light beating is most effective to observe the very weak light of Brillouin scattering. In the investigation by this Grantin-Aid,we obtained various important results which are summarized as follows.(a) We established the means to measure the phonon velocity and absorption in transparent solids at the frequency range up to 2GHz. The Gruneisen constant which represents the strength of phonon-phonon interaction, was estimated for sapphire from the results of hypersonic measurement. High frequency ultrasonic property was measured in GeO_2 glass. An absorption peak due to the structural relaxation was found around 600 MHz, which yields the distribution of the double well potential of oxygen atom in glass.(b) A new optical beating technique was developed to observe Brillouin scattering by thermal fluctuation of liquid surface.The range of the measurement was extended up to 1MHz, which is one decade higher than the previous works. This technique will be a powerful means to investigate the dynamic property of liquid surface.(c) We constracted several optical heterodyne systems to detect incoherent Brillouin scattering light by thermal phonons and obtained the characteristics and performance of each system through the preliminary test with them.

超声波光谱的基本要求是观察广泛频率范围内的速度和吸收。近年来，我们开发了多种实验技术，包括平凹超声谐振器和高分辨率布拉格反射（简称HRB）方法。该研究项目的目的是建立一种可用于测量高超声速范围内声子速度和衰变的新技术。为此，我们利用光跳动光谱来检测热声子的光散射。 HRB方法的成功表明，光跳动对于观察布里渊散射的非常弱的光是最有效的。在Grantin-Aid的研究中，我们获得了各种重要结果，总结如下：(a)我们建立了在高达2GHz的频率范围内测量透明固体中声子速度和吸收的方法。根据高超声速测量的结果估计了蓝宝石的格鲁内森常数，该常数代表声子-声子相互作用的强度。测量了GeO_2玻璃的高频超声性能。在600 MHz附近发现了由于结构弛豫而产生的吸收峰，这产生了玻璃中氧原子双阱势的分布。(b)开发了一种新的光学跳动技术来观察液体表面热波动的布里渊散射。测量范围扩大到1MHz，比之前的工作提高了10倍。该技术将成为研究液体表面动态特性的有力手段。(c)构建了几种利用热声子检测非相干布里渊散射光的光学外差系统，并通过初步测试获得了各系统的特性和性能。