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Osamu Matsuda
Faculty of Engineering　Applied Physics　Quantum Matter Physics
Professor
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Last Updated :2024/05/09

Researcher Profile and Settings

Affiliation

  • Faculty of Engineering　Applied Physics　Quantum Matter Physics

Job Title

  • Professor

Degree

  • Dr. Sci.（1991/03 Osaka University）

URL

J-Global ID

Research Interests

  • フォトルミネッセンス   カルコゲナイド   ポンプ・プローブ法   ピコ秒レーザー音響法   非破壊検査   電子格子相互作用   表面音響波   カンチレバーダイナミクス   原子間力顕微鏡   アモルファス   励起子   イメージング   走査プローブ顕微鏡   干渉計   異方性   吸着力   剪断音響波   2次元イメージング   ヘテロダイン検出法   緩和過程   液体中の音響波   UFM   時間分解測定   フォースカーブ   励起電子緩和過程   局所弾性率   キャリア輸送   差分法解析   phonon physics   semiconductor physics   scanning probe microscopy   ultrafast spectroscopy   solid state physics   

Research Areas

  • Nanotechnology/Materials / Applied physics - general
  • Nanotechnology/Materials / Optical engineering and photonics

Educational Organization

Academic & Professional Experience

  • 2022/04 - Today Division of Applied Physics, Faculty of Engineering, Hokkaido University Professor
  • 2007/04 - 2022/03 Division of Applied Physics, Faculty of Engineering, Hokkaido University Associate Professor
  • 1998/05 - 2007/03 Department of Applied Physics, Faculty of Engineering, Hokkaido University Associate Professor
  • 1991/04 - 1998/04 Department of Physics, Faculty of Science, Osaka University Research Associate

Association Memberships

  • THE JAPAN SOCIETY OF APPLIED PHYSICS   THE PHYSICAL SOCIETY OF JAPAN   

Research Activities

Published Papers

  • Hayato Takeda, Ryoya Minami, Osamu Matsuda, Oliver B. Wright, Motonobu Tomoda
    Applied Physics Express 2024/01/01
  • Takehiro Tachizaki, Jeremy J. Baumberg, Osamu Matsuda, Motonobu Tomoda, Hirotsugu Ogi, Oliver B. Wright
    Photoacoustics 34 100566 - 100566 2213-5979 2023/12
  • Motonobu Tomoda, Akira Toda, Osamu Matsuda, Vitalyi E. Gusev, Oliver B. Wright
    Photoacoustics 30 100459 - 100459 2213-5979 2023/04
  • Osamu Matsuda, Hiroaki Koga, Hiroki Nishita, Motonobu Tomoda, Paul H. Otsuka, Oliver B. Wright
    Photoacoustics 2023/04
  • Hayato Takeda, Eikai Murakami, Motonobu Tomoda, Osamu Matsuda, Kentaro Fujita, Oliver B. Wright
    Applied Physics Letters 2022/09/26
  • Ting Zhang, Eun Bok, Motonobu Tomoda, Osamu Matsuda, Jianzhong Guo, Xiaojun Liu, Oliver B Wright
    Applied Physics Letters 120 (16) 161701 - 161701 2022/04/18
  • Hai Jun Cho, Yuzhang Wu, Jiajun Qi, Yuna Kim, Hiromichi Ohta, Osamu Matsuda
    Journal of the Physical Society of Japan 91 (1) 0031-9015 2022/01/15
  • Yuta Imade, Vitalyi E. Gusev, Osamu Matsuda, Motonobu Tomoda, Paul H. Otsuka, Oliver B. Wright
    Nano Letters 21 (14) 6261 - 6267 1530-6984 2021/07/28
  • C. Li, R. T. Harley, P. G. Lagoudakis, O. B. Wright, O. Matsuda
    Physical Review B 2021/06/01
  • Osamu Matsuda, Kandai Tsutsui, Gwenaëlle Vaudel, Thomas Pezeril, Kentaro Fujita, Vitalyi Gusev
    Physical Review B 2020/06/22 [Refereed][Not invited]
  • Akira Ogasawara, Kentaro Fujita, Motonobu Tomoda, Osamu Matsuda, Oliver B. Wright
    Applied Physics Letters 116 (24) 241904 - 241904 0003-6951 2020/06/15 [Refereed][Not invited]
  • T. Devaux, H. Tozawa, P. H. Otsuka, S. Mezil, M. Tomoda, O. Matsuda, E. Bok, S. H. Lee, O. B. Wright
    Science Advances 6 (10) 2020/03/04 [Refereed][Not invited]
  • Kentaro Fujita, Motonobu Tomoda, Oliver B. Wright, Osamu Matsuda
    Applied Physics Letters 115 (8) 081905-1 - 5 2019/08/19 [Refereed][Not invited]
  • Qingnan Xie, Sylvain Mezil, Paul H. Otsuka, Motonobu Tomoda, Jérôme Laurent, Osamu Matsuda, Zhonghua Shen, Oliver B. Wright
    Nature Communications 10 (1) 2228-1 - 12 2019/05/20 [Refereed][Not invited]
  • Osamu Matsuda
    New Journal of Physics 20 (1) 013026-1 - 12 1367-2630 2018/01/22 [Refereed][Not invited]
     
    We extend time-domain imaging in acoustic metamaterials to gigahertz frequencies. Using a sample consisting of a regular array of ∼1 μm diameter silica microspheres forming a two-dimensional triangular lattice on a substrate, we implement an ultrafast technique to probe surface acoustic wave propagation inside the metamaterial area and incident on the metamaterial from a region containing no microspheres, which reveals the acoustic metamaterial dispersion, the presence of band gaps and the acoustic transmission properties of the interface. A theoretical model of this locally resonant metamaterial based on normal and shear-rotational resonances of the spheres fits the data well. Using this model, we show analytically how the sphere elastic coupling parameters influence the gap widths.
  • Matsuda, O., Pezeril, T., Chaban, I., Fujita, K., Gusev, V.
    Physical Review B 97 (6) 064301-1 - 11 2469-9969 2018 [Refereed][Not invited]
     
    Absorption of ultrashort laser pulses in a metallic grating deposited on a transparent sample launches coherent compression/dilatation acoustic pulses in directions of different orders of acoustic diffraction. Their propagation is detected by delayed laser pulses, which are also diffracted by the metallic grating, through the measurement of the transient intensity change of the first-order diffracted light. The obtained data contain multiple frequency components, which are interpreted by considering all possible angles for the Brillouin scattering of light achieved through multiplexing of the propagation directions of light and coherent sound by the metallic grating. The emitted acoustic field can be equivalently presented as a superposition of plane inhomogeneous acoustic waves, which constitute an acoustic diffraction grating for the probe light. Thus the obtained results can also be interpreted as a consequence of probe light diffraction by both metallic and acoustic gratings. The realized scheme of time-domain Brillouin scattering with metallic gratings operating in reflection mode provides access to wide range of acoustic frequencies from minimal to maximal possible values in a single experimental optical configuration for the directions of probe light incidence and scattered light detection. This is achieved by monitoring the backward and forward Brillouin scattering processes in parallel. Potential applications include measurements of the acoustic dispersion, simultaneous determination of sound velocity and optical refractive index, and evaluation of samples with a single direction of possible optical access.
  • Sylvain Mezil, Kentaro Fujita, Paul H. Otsuka, Motonobu Tomoda, Matt Clark, Oliver B. Wright, Osamu Matsuda
    Applied Physics Letters 111 (14) 144103 - 144103 0003-6951 2017/10/02 [Refereed][Not invited]
     
    We selectively generate chiral surface-acoustic whispering-gallery modes in the gigahertz range on a microscopic disk by means of an ultrafast time-domain technique incorporating a spatial light modulator. Active chiral control is achieved by making use of an optical pump spatial profile in the form of a semicircular arc, positioned on the sample to break the symmetry of clockwise-and counterclockwise-propagating modes. Spatiotemporal Fourier transforms of the interferometrically monitored two-dimensional acoustic fields measured to micron resolution allow individual chiral modes and their azimuthal mode order, both positive and negative, to be distinguished. In particular, for modes with 15-fold rotational symmetry, we demonstrate ultrafast chiral control of surface acoustic waves in a micro-acoustic system with picosecond temporal resolution. Applications include nondestructive testing and surface acoustic wave devices. Published by AIP Publishing.
  • Osamu Matsuda
    Nano Letters 17 (11) 6684 - 6689 1530-6984 2017/09/15 [Refereed][Not invited]
     
    Using polarization-resolved transient reflection spectroscopy, we investigate a metasurface consisting of coherently vibrating nanophotonic U-shaped split-ring meta-atoms that exhibit colocalized optical and mechanical resonances. With an array of these resonators formed of gold on glass, essentially miniature tuning forks, we monitor the visible-pump induced gigahertz oscillations in reflected infrared light intensity to probe the multimodal vibrational response. Numerical simulations of the associated transient deformations and strain fields elucidate the complex nanomechanical dynamics contributing to the ultrafast optical modulation and point to the role of acousto-plasmonic interactions through the opening and closing motion of the SRR gaps as the dominant effect. Applications include ultrafast acoustooptic modulator design and sensing.
  • Ulbricht, R., Sakuma, H., Imade, Y., Otsuka, P. H., Tomoda, M., Matsuda, O., Kim, H., Park, G. W., Wright, O. B.
    Applied Physics Letters 110 (9) 091910-1 - 5 0003-6951 2017 [Refereed][Not invited]
     
    The ultrafast modulation of light transmitted by a metamaterial making up an extraordinary optical transmission geometry is investigated by means of optical pump-probe spectroscopy. Using a sample consisting of a lattice of square nano-holes in a gold film on a glass substrate, we monitor the high-frequency oscillations in the intensity of transmitted infrared light. A variety of gigahertz acoustic modes, involving the opening and shutting motion of the holes as well as the straining of the glass substrate below the holes, are revealed to be active in the optical modulation. Numerical simulations of the transient deformations and strain fields elucidate the nature of the vibrational modes contributing most strongly to the variations in optical transmission, and point to the hole-area modulation as the dominant effect. Potential applications include ultrafast acousto-optic modulators. Published by AIP Publishing.
  • Dehoux T, Ishikawa K, Otsuka PH, Tomoda M, Matsuda O, Fujiwara M, Takeuchi S, Veres IA, Gusev VE, Wright OB
    Light, science & applications 5 (5) e16082  2095-5545 2016/05 [Refereed][Not invited]
  • Kouyate, Mansour, Pezeril, Thomas, Gusev, Vitalyi, Matsuda, Osamu
    Journal of the Optical Society of America B-Optical Physics 33 (12) 2634 - 2648 0740-3224 2016 [Refereed][Not invited]
     
    A theoretical formalism describing the heterodyne detection of plane inhomogeneous shear acoustic waves by probe laser-induced gratings is developed. An inhomogeneous plane shear acoustic wave is a purely shear wave with a plane phase front and mechanical displacement vector, which is sinusoidally spatially modulated in magnitude. It could be generated by laser-induced gratings and could be useful for the acoustic testing of sub-micrometer thick membranes and coatings in the gigahertz frequency range. The theory reveals the potential advantages and disadvantages of this wave application in non-destructive testing of materials and fundamental research from the point of view of the feasibility of their experimental detection. (C) 2016 Optical Society of America
  • Dehoux, Thomas, Ishikawa, Kenichi, Otsuka, Paul H., Tomoda, Motonobu, Matsuda, Osamu, Fujiwara, Masazumi, Takeuchi, Shigeki, Veres, Istvan A., Gusev, Vitalyi E., Wright, Oliver B.
    Light-Science & Applications 5 E16082-1 - 7 2047-7538 2016 [Refereed][Not invited]
     
    By means of an ultrafast optical technique, we track focused gigahertz coherent phonon pulses in objects down to sub-micron in size. Infrared light pulses illuminating the surface of a single metal-coated silica fibre generate longitudinal-phonon wave packets. Reflection of visible probe light pulses from the fibre surface allows the vibrational modes of the fibre to be detected, and Brillouin optical scattering of partially transmitted light pulses allows the acoustic wavefronts inside the transparent fibre to be continuously monitored. We thereby probe acoustic focusing in the time domain resulting from generation at the curved fibre surface. An analytical model, supported by three-dimensional simulations, suggests that we have followed the focusing of the acoustic beam down to a similar to 150-nm diameter waist inside the fibre. This work significantly narrows the lateral resolution for focusing of picosecond acoustic pulses, normally limited by the diffraction limit of focused optical pulses to similar to 1 mu m, and thereby opens up a new range of possibilities including nanoscale acoustic microscopy and nanoscale computed tomography.
  • Mezil, Sylvain, Chonan, Kazuki, Otsuka, Paul H., Tomoda, Motonobu, Matsuda, Osamu, Lee, Sam H., Wright, Oliver B.
    Scientific Reports 6 33380-1 - 11 2045-2322 2016 [Refereed][Not invited]
     
    Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths lambda similar to 3-50 mu m, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one-and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to similar to 23 and similar to 8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging.
  • Osamu Matsuda, Oliver B. Wright
    Phononic Crystals: Fundamentals and Applications 192 - 213 2015/07/28 [Refereed][Not invited]
  • Matsuda Osamu, Mezil Sylvain, Otsuka Paul H., Kaneko Shogo, Wright Oliver B., Tomoda Motonobu
    Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 70 1253 - 1253 2189-079X 2015
  • Liu, Liwang, Zhong, Kuo, Munro, Troy, Alvarado, Salvador, Cote, Renaud, Creten, Sebastiaan, Fron, Eduard, Ban, Heng, Van der Auweraer, Mark, Roozen, N. B., Matsuda, Osamu, Glorieux, Christ
    Journal of Applied Physics 118 (18) 184906-1 - 12l 0021-8979 2015 [Refereed][Not invited]
     
    Neural network recognition of features of the fluorescence spectrum of a thermosensitive probe is exploited in order to achieve fluorescence-based thermometry with an accuracy of 200mK with 100MHz bandwidth, and with high robustness against fluctuations of the probe laser intensity used. The concept is implemented on a rhodamine B dyed mixture of copper chloride and glycerol, and the temperature dependent fluorescence is investigated in the temperature range between 234K and 311 K. The spatial dependence of the calibrated amplitude and phase of photothermally induced temperature oscillations along the axis of the excitation laser are determined at different modulation frequencies. The spatial and frequency dependence of the extracted temperature signals is well fitted by a 1D multi-layer thermal diffusion model. In a time domain implementation of the approach, the gradual temperature rise due to the accumulation of the DC component of the heat flux supplied by repetitive laser pulses as well the immediate transient temperature evolution after each single pulse is extracted from acquired temporal sequences of fluorescence spectra induced by a CW green laser. A stroboscopic implementation of fluorescence thermometry, using a pulsed fluorescence evoking probe laser, is shown to achieve remote detection of temperature changes with a time resolution of 10 ns. (C) 2015 AIP Publishing LLC.
  • Wright, Oliver B., Matsuda, Osamu
    Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences 373 (2049) 20140364-1 - 18 1364-503X 2015 [Refereed][Not invited]
     
    In this paper, we review results obtained by ultrafast imaging of gigahertz surface acoustic waves in surface phononic crystals with one- and two-dimensional periodicities. By use of quasi-point-source optical excitation, we show how, from a series of images that form a movie of the travelling waves, the dispersion relation of the acoustic modes, their corresponding mode patterns and the position and widths of phonon stop bands can be obtained by temporal and spatio-temporal Fourier analysis. We further demonstrate how one can follow the temporal evolution of phononic eigenstates in k-space using data from phononic-crystal waveguides as an example. (C) 2015 The Author(s) Published by the Royal Society. All rights reserved.
  • Matsuda, Osamu, Kaneko, Shogo, Wright, Oliver B., Tomoda, Motonobu
    Ieee Transactions on Ultrasonics Ferroelectrics and Frequency Control 62 (3) 584 - 595 0885-3010 2015 [Refereed][Not invited]
     
    We describe a way to generate and detect arbitrary frequency components in time-resolved surface acoustic wave imaging based on optical pumping and probing with a periodic light source. The detailed theory of the technique, based on beam modulation and Fourier analysis, for a variety of possible experimental configurations is presented, followed by experimental data for a glass substrate covered with a thin gold film. We show how the acoustic dispersion relation can be obtained to arbitrary frequency resolution, not limited by the laser pulse repetition rate.
  • Danworaphong, Sorasak, Tomoda, Motonobu, Matsumoto, Yuki, Matsuda, Osamu, Ohashi, Toshiro, Watanabe, Hiromu, Nagayama, Masafumi, Gohara, Kazutoshi, Otsuka, Paul H., Wright, Oliver B.
    Applied Physics Letters 106 (16) 163701-1 - 5 0003-6951 2015 [Refereed][Not invited]
     
    We use picosecond ultrasonics to image animal cells in vitro-a bovine aortic endothelial cell and a mouse adipose cell-fixed to Ti-coated sapphire. Tightly focused ultrashort laser pulses generate and detect GHz acoustic pulses, allowing three-dimensional imaging (x, y, and t) of the ultrasonic propagation in the cells with similar to 1 mu m lateral and similar to 150 nm depth resolutions. Time-frequency representations of the continuous-wavelet-transform amplitude of the optical reflectivity variations inside and outside the cells show GHz Brillouin oscillations, allowing the average sound velocities of the cells and their ultrasonic attenuation to be obtained as well as the average bulk moduli. (C) 2015 AIP Publishing LLC.
  • Xiong, Jichuan, Xu, Xiaodong, Glorieux, Christ, Matsuda, Osamu, Cheng, Liping
    Review of Scientific Instruments 86 (5) 053107-1 - 8 0034-6748 2015 [Refereed][Not invited]
     
    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm x 17 mm area on an aluminum plate was visualized with 520 x 696 pixels of the CCD sensor, yielding a spatial resolution of 33 mu m. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz. (C) 2015 AIP Publishing LLC.
  • Mezil, Sylvain, Otsuka, Paul H., Kaneko, Shogo, Wright, Oliver B., Tomoda, Motonobu, Matsuda, Osamu
    Optics Letters 40 (10) 2157 - 2160 0146-9592 2015 [Refereed][Not invited]
     
    Using an ultrafast optical technique with enhanced frequency control, we image surface-acoustic whispering-gallery-like modes in a microscopic disk at various frequencies up to 1 gigahertz (GHz), allowing experimental determination of their dispersion. This is made possible by intensity-modulated optical pumping and probing with a periodic femtosecond light source. Spatiotemporal Fourier transforms of the two-dimensional acoustic fields measured to micron resolution allow us to isolate individual whispering-gallery modes of first and second radial order as well as their mode patterns and Q factors to unprecedented frequency resolution. We thereby demonstrate arbitrary-frequency ultrafast control and imaging of a micro-acoustic system with an optical time-resolved technique. Applications include quality control of surface acoustic wave filters in telecommunications. (C) 2015 Optical Society of America
  • Matsuda, Osamu, Larciprete, Maria Cristina, Li Voti, Roberto, Wright, Oliver B.
    Ultrasonics 56 3 - 20 0041-624X 2015 [Refereed][Not invited]
     
    The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned. (C) 2014 Elsevier B.V. All rights reserved.
  • Otsuka, P. H., Chinbe, R., Tomoda, M., Matsuda, O., Veres, I. A., Lee, J. -H., Yoon, J. -B., Wright, O. B.
    Journal of Applied Physics 117 (24) 245308-1 - 6 0021-8979 2015 [Refereed][Not invited]
     
    We investigate surface phonon propagation in a triangular-lattice phononic crystal of microscopic holes in a gold-coated polymer by time-resolved two-dimensional imaging and by finite-element simulations at sub-gigahertz frequencies. The simulations allow the effects of exciting different points in the crystal lattice to be studied in real space, and also in k-space by spatiotemporal Fourier analysis. The acoustic field in a sub-surface plane below the reach of the holes is also revealed in real-and k-spaces. In addition, we demonstrate pitfalls in the analysis of k-space data when searching for the presence of band gaps. Applications include surface-acoustic wave filter quality control. (C) 2015 AIP Publishing LLC.
  • Tomoda, M., Dehoux, T., Iwasaki, Y., Matsuda, O., Gusev, V. E., Wright, O. B.
    Scientific Reports 4 4790-1 - 5 2045-2322 2014 [Refereed][Not invited]
     
    Mechanical contacts are crucial to systems in engineering, electronics and biology. The microscopic nature of the contacting surfaces determines how they mesh on the nanoscale. There is thus much interest in methods that can map the actual area of two surfaces in contact-the real contact area during the loading or unloading phases. We address this problem using an ultrafast optical technique to generate non-equilibrium electrons that diffuse across a nanoscale mechanical contact between two thin gold films deposited on sapphire. We image this process in the contact and near-contact regions to micron resolution in situ using transient optical reflectivity changes on femtosecond time scales. By use of a model of the ultrashort-time electron dynamics, we account for an up to similar to 40%dropin the transient optical reflectivity change on contact. We thereby show how the real contact area of a nanoscale contact can be mapped. Applications include the probing of microelectronic mechanical devices.
  • Kaneko, S., Tomoda, M., Matsuda, O.
    Aip Advances 4 (1) 017124-1 - 8 2158-3226 2014 [Refereed][Not invited]
     
    We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
  • Tomoda, Motonobu, Matsueda, Shinnosuke, Otsuka, Paul H., Matsuda, Osamu, Veres, Istvan A., Gusev, Vitalyi E., Wright, Oliver B.
    New Journal of Physics 16 103029-1 - 9 1367-2630 2014 [Refereed][Not invited]
     
    Using an ultrafast optical technique we image near-gigahertz flexural acoustic waves propagating in a thin gold wedge deposited on an ultrathin silicon nitride slab. Temporal Fourier transforms of the imaged data in two dimensions allow individual frequencies to be accessed. The wave fronts associated with antisymmetric Lamb waves bend towards the thin end of the wedge. This behaviour is mimicked with an analytical model based on sections of a linear wedge. We also conduct numerical simulations which show good agreement with the experimental results.
  • Matsuda, O., Tomoda, M., Tachizaki, T., Koiwa, S., Ono, A., Aoki, K., Beardsley, R. P., Wright, O. B.
    Journal of the Optical Society of America B-Optical Physics 30 (7) 1911 - 1921 0740-3224 2013 [Refereed][Not invited]
     
    We describe an ultrafast optical technique to quantitatively detect picosecond ultrasonic displacements of solid surfaces, thus giving access to the longitudinal strain pulse shape. Transient optical reflectance changes recorded at oblique optical incidence with a common-path interferometric configuration based on ultrafast ellipsometry monitor gigahertz coherent phonon pulses. We demonstrate for a tungsten film the quantitative extraction of the strain pulse shape free of distortions arising from the photoelastic effect, and analyze the results with the two-temperature model to obtain the value g approximate to 3 x 10(17) Wm(-3) K-1 for the electron-phonon coupling constant. Analysis of the data also reveals a thermo-optic contribution. (C) 2013 Optical Society of America
  • Kelf, T. A., Hoshii, W., Otsuka, P. H., Sakuma, H., Veres, I. A., Cole, R. M., Mahajan, S., Baumberg, J. J., Tomoda, M., Matsuda, O., Wright, O. B.
    New Journal of Physics 15 023013-1 - 14 1367-2630 2013 [Refereed][Not invited]
     
    We image the gigahertz vibrational modes of a plasmonic-phononic crystal at sub-micron resolution by means of an ultrafast optical technique, using a triangular array of spherical gold nanovoids as a sample. Light is strongly coupled to the plasmonic modes, which interact with the gigahertz phonons by a process akin to surface-enhanced stimulated Brillouin scattering. A marked enhancement in the observed optical reflectivity change at the centre of a void on phononic resonance is likely to be caused by this mechanism. By comparison with numerical simulations of the vibrational field, we identify resonant breathing deformations of the voids and elucidate the corresponding mode shapes. We thus establish scanned optomechanical probing of periodic plasmonic-phononic structures as a new means of investigating their coupled excitations on the nanoscale. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
  • Veres, I. A., Berer, T., Matsuda, O.
    Journal of Applied Physics 114 (8) 083519-1 - 11 0021-8979 2013 [Refereed][Not invited]
     
    In this work, the calculation of complex band structures of two-dimensional bulk phononic crystals (2DPCs) is discussed by the finite element method. A modification of the classical ω (k) approach - calculating the unknown frequencies for a real wave number - is modified to a k (ω) solution, which allows the evaluation of complex wave numbers for real frequencies. The dispersion relation of a 2DPC in a square lattice is presented and it is shown that the problem reduces to a polynomial eigenvalue problem with quadratic and quartic eigenvalue problems in the Γ - X - M - Γ directions. The developed method is applied for solid-vacuum PCs made of isotropic materials consisting cylindrical holes. Complex dispersion diagrams are calculated with various Poisson's ratios and the mode shapes of the propagating and the evanescent modes are presented. The significance of the complex bands is discussed. © 2013 AIP Publishing LLC.
  • Every, A. G., Maznev, A. A., Grill, W., Pluta, M., Comins, J. D., Wright, O. B., Matsuda, O., Sachse, W., Wolfe, J. P.
    Wave Motion 50 (8) 1197 - 1217 0165-2125 2013 [Refereed][Not invited]
     
    Crystal acoustics is a field that has engaged the attention of theoreticians and experimentalists alike for decades and more. Many striking effects have been revealed, and elegant analytical techniques applied to their interpretation. This article is oriented towards the experimental aspects of the field and the interpretation of the phenomena that have been observed. Particular attention is given to reviewing the techniques that have probed the intricacy of acoustic wave propagation in crystals, including phonon imaging, laser- and capillary-fracture-generated ultrasound, transmission acoustic microscopy and surface Brillouin scattering, and a selection of results obtained with these techniques is presented. Some of these studies pertain to bulk waves and others to surface acoustic waves. The interpretation of far-field observations is carried out within the ray approximation, and elastodynamic Green's functions are invoked in the interpretation of near-field results. Extensive use is made of the acoustic-slowness and wave surfaces, in particular features such as acoustic axes, with their attendant polarization singularities, and folds in the wave surface. (C) 2013 Elsevier B.V. All rights reserved.
  • Otsuka, P. H., Nanri, K., Matsuda, O., Tomoda, M., Profunser, D. M., Veres, I. A., Danworaphong, S., Khelif, A., Benchabane, S., Laude, V., Wright, O. B.
    Scientific Reports 3 3351-1 - 5 2045-2322 2013 [Refereed][Not invited]
     
    Control of sound in phononic band-gap structures promises novel control and guiding mechanisms. Designs in photonic systems were quickly matched in phononics, and rows of defects in phononic crystals were shown to guide sound waves effectively. The vast majority of work in such phononic guiding has been in the frequency domain, because of the importance of the phononic dispersion relation in governing acoustic confinement in waveguides. However, frequency-domain studies miss vital information concerning the phase of the acoustic field and eigenstate coupling. Using a wide range of wavevectors k, we implement an ultrafast technique to probe the wave field evolution in straight and L-shaped phononic crystal surface-phonon waveguides in real- and k-space in two spatial dimensions, thus revealing the eigenstate-energy redistribution processes and the coupling between different frequency-degenerate eigenstates. Such use of k-t space is a first in acoustics, and should have other interesting applications such as acoustic-metamaterial characterization.
  • Istvan A. Veres, Thomas Berer, Osamu Matsuda
    IEEE International Ultrasonics Symposium, IUS 729 - 732 1948-5719 2013 [Refereed][Not invited]
     
    The calculation of complex band structures for surface gratings (one dimensional phononic crystals) and for two dimensional phononic crystals is discussed in the presented paper. We show an extension of the finite element method and the semi-analytical finite element method based on the dynamic condensation to achieve this aim. Complex band structures are particularly important for surface gratings, since the folded surface waves become evanescent beyond the sound cone. This behavior and the complex interconnections between the real propagating modes are discussed. The presence of an evanescent mode within the complete stop band is shown for surface gratings. This describes the spatial decay of the elastic waves inside the stop band. The presented method is extended for two dimensional phononic crystals with square lattices whereby the different orientations of the wave vector lead to polynomial eigenvalue problems including quadratic and quartic eigenvalue problems. © 2013 IEEE.
  • Sermeus, J., Matsuda, O., Salenbien, R., Verstraeten, B., Fivez, J., Glorieux, C.
    International Journal of Thermophysics 33 (10-11) 2145 - 2158 0195-928X 2012 [Refereed][Not invited]
     
    In recent decades, the impulsive stimulated scattering (ISS) method, which is based on photothermal and photoacoustic phenomena, has been successfully used to simultaneously investigate the thermal and elastic properties in a four-wave mixing configuration, both in transmission in semitransparent materials and on reflecting surfaces of solids. In this report, an extension of the technique is proposed to study a laser-induced thermoelastic response at the free surface of glass-forming liquids. The employed all-optical configuration allows extraction of information about the acoustic shear modulus in the MHz frequency range, and hence is complementary to the classical ISS configuration in the transmission mode, which is suitable to study the relaxation of the longitudinal acoustic modulus, and to another earlier reported ISS configuration, which is exciting and probing laser-induced thermoelastic phenomena at a liquid-solid interface. A theoretical model is presented and numerically illustrated for the glass transition of glycerol, and experimentally validated for water at room temperature.
  • Veres, I. A., Profunser, D. M., Maznev, A. A., Every, A. G., Matsuda, O., Wright, O. B.
    New Journal of Physics 14 123015-1 - 28 1367-2630 2012 [Refereed][Not invited]
     
    We use locally-excited gigahertz surface phonon wavepackets in microscopic line structures of different pitches to reveal profound anisotropy in the radiation pattern of a point source in a grating. Time-domain data obtained by an ultrafast optical imaging technique and by numerical simulations are Fourier transformed to obtain frequency-filtered real-space acoustic field patterns and k-space phononic band structure. The numerically-obtained k-space images are processed to reveal an intriguing double-horn structure in the lowest-order group-velocity surface, which explains the observed non-propagation sectors bounded by caustics, noted at frequencies above the bottom of the first stop band. We account for these phonon-focusing effects, analogous to collimation effects previously observed in two-and three-dimensional lattices, with a simple analytical model of the band structure based on a plane wave expansion. As the frequency is increased, a transition to dominant waveguiding effects along the lines is also documented.
  • Sakuma, Hirotaka, Tomoda, Motonobu, Otsuka, Paul H., Matsuda, Osamu, Wright, Oliver B., Fukui, Takashi, Tomioka, Katsuhiro, Veres, Istvan A.
    Applied Physics Letters 100 (13) 131902-1 - 3 0003-6951 2012 [Refereed][Not invited]
     
    We investigate the vibrational modes of a triangular array of anisotropic, hexagonal GaAs nanopillars on a GaAs substrate through ultrafast changes in optical reflectivity. By comparison with simulations, we identify GHz resonances, mode shapes, and damping. In addition, by varying the pillar diameter, height, and pitch, we distinguish collective and localized modes. A proper understanding of substrate-attached nanostructure dynamics will lead to better characterization of nanosensors based on perturbations to vibrational resonances. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3696380]
  • Veres, I. A., Berer, T., Matsuda, O., Burgholzer, P.
    Journal of Applied Physics 112 (5) 053504-1 - 7 0021-8979 2012 [Refereed][Not invited]
     
    Focusing and subwavelength imaging of surface acoustic waves (SAWs) through a phononic crystal flat lens are discussed in the presented work. Experimental and numerical wave fields are obtained in the time-domain by an optical technique and by numerical simulations. Spatial distributions of the acoustic field are accessed using a temporal Fourier transform. The revealed focusing of the elastic waves in the first band of the crystal is governed by the concave equifrequency contour of the leaky-Rayleigh wave. The spatial distributions of the experimental and numerical acoustic fields also unfold subwavelength imaging of SAWs. Numerical simulations show that the imaging quality can be improved by embedding the flat lens into a medium with higher wave velocity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747931]
  • Wright, Oliver B., Veres, Istvan A., Profunser, Dieter M., Matsuda, Osamu, Culshaw, Brian, Lang, Udo
    Chinese Journal of Physics 49 (1) 16 - 22 2011 [Refereed][Not invited]
  • Danworaphong, S., Kelf, T. A., Matsuda, O., Tomoda, M., Tanaka, Y., Nishiguchi, N., Wright, O. B., Nishijima, Y., Ueno, K., Juodkazis, S., Misawa, H.
    Applied Physics Letters 99 (20) 201910-1 - 3 0003-6951 2011 [Refereed][Not invited]
     
    We image gigahertz surface acoustic waves normally incident on a microscopic linear array of triangular holes-a generic "acoustic diode" geometry-with a real-time ultrafast optical technique. Spatiotemporal Fourier transforms reveal wave diffraction orders in k-space. Squared amplitude reflection and transmission coefficients for incidence on both sides of the array are evaluated and compared with numerical simulations. We thereby directly demonstrate acoustic rectification with an asymmetric structure. (C) 2011 American Institute of Physics. [doi:10.1063/1.3662930]
  • Kelf, T. A., Tanaka, Y., Matsuda, O., Larsson, E. M., Sutherland, D. S., Wright, O. B.
    Nano Letters 11 (9) 3893 - 3898 1530-6984 2011 [Refereed][Not invited]
     
    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We elucidate the corresponding mode shapes and find that the substrate plays an important role in determining the mode damping. This study demonstrates the need for a plasmonic nano-optics approach to understand the optical excitation and detection mechanisms for the vibrations of plasmonic nanostructures.
  • Veres, Istvan A., Profunser, Dieter M., Wright, Oliver B., Matsuda, Osamu, Culshaw, Brian
    Chinese Journal of Physics 49 (1) 534 - 541 2011 [Refereed][Not invited]
  • Maznev, A. A., Wright, O. B., Matsuda, O.
    New Journal of Physics 13 013037-1 - 11 1367-2630 2011 [Refereed][Not invited]
     
    We map the band structure of surface acoustic modes of a periodic array of copper lines embedded in a SiO2 film on a silicon substrate by means of the laser-induced transient grating technique. A detailed map of the lowest sheet of the omega(k) surface and partial maps of two higher-order sheets are obtained. We discuss the topology of the omega(k) surface and explain how it arises from the Rayleigh and Sezawa modes of the film/substrate system. In the vicinity of the bandgap formed at the Brillouin zone boundary, the first and second dispersion sheets take the form of a saddle and a bowl, respectively, in agreement with a weak perturbation model. The shape of the third dispersion sheet, however, appears to defy expectations based on the perturbation approach. In particular, it contains minima located off the symmetry directions, which implies the existence of zero group velocity modes with an obliquely directed wavevector.
  • Oliver B. Wright, Istvan A. Veres, Dieter M. Profunser, Osamu Matsuda, Brian Culshaw, Udo Lang
    SMART NANO-MICRO MATERIALS AND DEVICES 8204 820425-1 - 6 0277-786X 2011 [Not refereed][Not invited]
     
    Using ultrashort pulsed optical excitation and interferometric detection, we image ultrahigh- frequency surface acoustic waves on two-dimensional (2D) phononic crystals in the time domain. The samples consist of a square lattice of air-filled holes etched in a silicon substrate. Good agreement with time-domain finite element numerical simulations is obtained. The dispersion relation is derived and stop bands are revealed by means of Fourier transforms. The wave fields corresponding to acoustic eigenmodes at specific frequencies are also presented.
  • Istvan A. Veres, Bernhard Reitinger, Thomas Berer, Peter Burgholzer, Oliver B. Wright, Osamu Matsuda
    2011 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) 2011 Vol.2 1312 - 1315 1948-5719 2011 [Not refereed][Not invited]
     
    We investigate numerically and experimentally the negative refraction of surface acoustic waves in two-dimensional phononic crystals in the MHz range. We performed high-performance time-domain simulations of propagating broadband surface acoustic waves with the Finite Element Method (FEM) and spatio-temporal imaging by means of pulsed optical excitation and interferometric detection. Experimental and numerical evidence is found for negative refraction from surface wave focusing at particular frequencies after wave propagation through a parallel-sided phononic crystal layer. Obliquely incident plane waves on a phononic crystal were also investigated by numerical simulations. The transmitted waves show a clear shift of the wave front at particular frequencies, providing further evidence for negative refraction of the surface acoustic waves.
  • Otsuka, P. H., Matsuda, O., Tomoda, M., Wright, O. B.
    Journal of Applied Physics 108 (12) 123508-1 - 5 0021-8979 2010 [Refereed][Not invited]
     
    We use an ultrafast optical pump and probe technique to investigate the propagation of subgigahertz surface acoustic waves on a 1 mm diameter glass sphere with an aluminum coating. A fiber-based pump setup generates the surface waves and a common-path interferometer images them in the time domain over the sphere surface as they pass through the pole opposite the source of excitation. Fourier analysis allows the acoustic spectrum of the acoustic source to be extracted and waves traveling in opposite directions to be isolated. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3517076]
  • Hurley, D. H., Wright, O. B., Matsuda, O., Shinde, S. L.
    Journal of Applied Physics 107 (2) 023521-1 - 5 0021-8979 2010 [Refereed][Not invited]
     
    We use ultrashort optical pulses to microscopically image carrier and thermal diffusion in two spatial dimensions in pristine and mechanically polished surfaces of crystalline silicon. By decomposing changes in reflectivity in the latter sample into a transient component that varies with delay time and a steady-state component that varies with pump chopping frequency, the influence of thermal diffusion is isolated from that of carrier diffusion and recombination. Additionally, studies using carrier injection density as a parameter are used to clearly identify the carrier recombination pathway.
  • Maznev, A. A., Kelf, Timothy A., Tomoda, Motonobu, Matsuda, Osamu, Wright, Oliver B.
    Journal of Applied Physics 107 (3) 033521-1 - 5 0021-8979 2010 [Refereed][Not invited]
     
    Laser-induced transient grating measurements and ultrafast optical pump-probe imaging of surface acoustic waves near a linear boundary between copper and silica films on a silicon substrate indicate the presence of a boundary-localized mode with a phase velocity slightly below the Rayleigh wave velocity on the copper film. We analyze in detail the dispersion of this localized mode in comparison with that of the Rayleigh waves in the surrounding materials. The existence of the localized mode is ascribed to the nonuniformity of the copper film thickness near its edge resulting from polishing during fabrication.
  • Tachizaki, Takehiro, Matsuda, Osamu, Maznev, Alex A., Wright, Oliver B.
    Physical Review B 81 (16) 165434-1 - 5 1098-0121 2010 [Refereed][Not invited]
     
    Broadband coherent surface phonon wave packets up to 1 GHz in a microscopic embedded disk are excited and dynamically imaged with ultrashort optical pulses. We isolate a whispering-gallery-like mode using a technique involving quadrature detection of the out-of-plane surface motion on modulating the optical excitation beam. The eigenmode distribution is obtained from spatiotemporal Fourier transforms and a radial-azimuthal decomposition demonstrates the selective excitation of a mode with 26-fold rotational symmetry and allows an estimate of the cavity Q factor to be made.
  • Saito, Taiki, Matsuda, Osamu, Tomoda, Motonobu, Wright, Oliver B.
    Journal of the Optical Society of America B-Optical Physics 27 (12) 2632 - 2638 0740-3224 2010 [Refereed][Not invited]
     
    This paper presents experiments and in-depth analysis of the imaging of surface acoustic waves by means of the photoelastic effect. Gigahertz surface acoustic waves, generated by optical pump pulses in a thin gold film on a glass substrate, are imaged in the time domain by monitoring ultrafast changes in optical reflectivity. We demonstrate how images of the in-plane acoustic shear strain component can be obtained by measurements with two different optical probe pulse polarizations incident from the substrate side. (C) 2010 Optical Society of America
  • Osamu Matsuda, Oliver B. Wright
    Journal of the Vacuum Society of Japan 53 (5) 336 - 343 1882-2398 2010 [Refereed][Not invited]
     
    Ultrashort light pulses absorbed in a medium generate both bulk and surface acoustic waves: we focus here on imaging the surface waves and on monitoring the bulk acoustic waves that propagate in the depth direction. This is done in the time domain by delayed probe light pulses. For the bulk acoustic waves, the generated frequency ranges up to 1 THz. Some studies concerning the ultrafast electron-phonon relaxation in metal films, high frequency generation in semiconductor quantum wells, and high frequency shear acoustic wave generation and detection are reviewed here. For the surface acoustic waves the generated frequency ranges up to 1 GHz, and time-resolved two-dimensional images of the propagation are obtained with micron lateral spatial resolution. This imaging method is applied to anisotropic crystals and phononic crystals to elucidate their acoustic properties.
  • Dehoux, T., Kelf, T. A., Tomoda, M., Matsuda, O., Wright, O. B., Ueno, K., Nishijima, Y., Juodkazis, S., Misawa, H., Tournat, V., Gusev, V. E.
    Optics Letters 35 (7) 940 - 940 2010 [Refereed][Not invited]
  • Osamu Matsuda, Oliver B. Wright
    Journal of the Vaccum Society of Japan 53 (5) 336 - 343 1882-2398 2010 [Refereed][Not invited]
  • VERES Istvan A, PROFUNSER Dieter M, WRIGHT Oliver B, MATSUDA Osamu, LANG Udo
    IEEE Int Ultrason Symp 2009 Vol.2 1032 - 1035 1948-5719 2009/09 [Not refereed][Not invited]
  • Dehoux, T., Kelf, T. A., Tomoda, M., Matsuda, O., Wright, O. B., Ueno, K., Nishijima, Y., Juodkazis, S., Misawa, H., Tournat, V., Gusev, V. E.
    Optics Letters 34 (23) 3740 - 3742 0146-9592 2009 [Refereed][Not invited]
     
    We use ultrashort optical pulses to excite and detect vibrations of single silica spheres with a diameter of 5 mu m placed at the surface of an acoustically mismatched substrate. In addition to the photoelastic detection of picosecond longitudinal acoustic pulses propagating inside the bulk, we detect gigahertz acoustic resonances of the sphere through probe beam defocusing. The mode frequencies are in close accord with those calculated from the elastic vibrations of a free sphere. We also record a resonant enhancement in the amplitude of specific modes of two touching spheres. (C) 2009 Optical Society of America
  • Profunser, Dieter M., Muramoto, Eiji, Matsuda, Osamu, Wright, Oliver B., Lang, Udo
    Physical Review B 80 (1) 014301-1 - 7 1098-0121 2009 [Refereed][Not invited]
     
    Surface acoustic wave propagation on a microscopic two-dimensional phononic crystal consisting of a square lattice of holes is imaged in two dimensions and in real time at frequencies up to 1 GHz by means of pulsed ultrashort optical excitation and detection. The acoustic dispersion relation obtained by spatiotemporal Fourier transforms shows the opening of stop bands at the zone boundaries for surface waves traveling parallel to the phononic crystal axes. We detect pronounced Bloch harmonics above the stop band, and reveal the spatial mode distributions at different frequencies. We also observe phonon collimation for frequencies at which the constant-frequency surfaces become square in shape.
  • D. H. Hurley, O. B. Wright, O. Matsuda, Brian E. McCandless, Subhash Shinde
    ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS XIII 7214 0277-786X 2009 [Refereed][Not invited]
     
    A series of experiments have been conducted that microscopically image thermal diffusion and surface acoustic phonon propagation within a single crystallite of a polycrystalline Si sample. The experimental approach employs ultrashort optical pulses to generate an electron-hole plasma and a second probe pulse is used to image the evolution of the plasma. By decomposing the signal into a component that varies with delay time and a steady state component that varies with pump modulation frequency, the respective influence of carrier recombination and thermal diffusion are identified. Additionally, the coherent surface acoustic phonon component to the signal is imaged using a Sagnac interferometer to monitor optical phase.
  • 3P1-18
    Tomoda Motonobu, Matsueda Shinnosuke, Wright Oliver B, Matsuda Osamu, Nishijima Yoshiaki, Ueno Kosei, Saulius Juodkazis, Misawa Hiroaki
    Proceedings of Symposium on Ultrasonic Electronics 2009 [Not refereed][Not invited]
  • Wright, O. B., Perrin, B., Matsuda, O., Gusev, V. E.
    Physical Review B 78 (2) 024303-1 - 11 1098-0121 2008/07/25 [Refereed][Not invited]
     
    Ultrashort optical pulses are used to excite and interferometrically detect picosecond longitudinal-acoustic pulses in thin films of liquid mercury sandwiched between sapphire plates. We show that the shape of the strain pulses in the mercury can be directly measured through ultrafast changes in optical reflectivity. By analyzing consecutive acoustic echoes, we derive the dispersion of the ultrasonic attenuation and sound velocity for this liquid at frequencies up to 10 GHz. Significant effects of structural relaxation are observed and are compared to a simple model that indicates the presence of picosecond relaxation times in mercury. © 2008 The American Physical Society.
  • Matsuda, O., Wright, O. B., Hurley, D. H., Gusev, V., Shimizu, K.
    Physical Review B 77 (22) 224110-1 - 16 1098-0121 2008 [Refereed][Not invited]
     
    Measurements on a film of silica on crystalline zinc using picosecond laser acoustics are theoretically analyzed to quantitatively explain the generation and detection of picosecond shear and longitudinal-acoustic waves. The theory encompasses the scattering of obliquely incident probe light of arbitrary polarization by a depth-dependent anisotropic permittivity modulation in a multilayer, including terms arising from the photoelastic effect, interface displacements, and local rotations. Sound velocities, ultrasonic attenuation, and photoelastic constants are experimentally derived.
  • Hurley, D. H., Lewis, R., Wright, O. B., Matsuda, O.
    Applied Physics Letters 93 (11) 1131011 - 3 0003-6951 2008 [Refereed][Not invited]
     
    We demonstrate the coherent generation and control of gigahertz acoustic phonons with ultrafast optical pulses. Two distinct acoustic phonon modes, a surface acoustic phonon mode and a longitudinal acoustic phonon mode, are generated simultaneously by irradiating nanolithographic absorption gratings on semiconductor substrates. Two material systems are examined: suboptical wavelength aluminum absorption gratings on Si and GaAs substrates. Constructive and complete destructive interference conditions are demonstrated using two pump pulses derived from a single Michelson interferometer. (C) 2008 American Institute of Physics.
  • Fujikura, Takashi, Matsuda, Osamu, Profunser, Dieter M., Wright, Oliver B., Masson, Jeremy, Ballandras, Sylvain
    Applied Physics Letters 93 (26) 261101-1 - 3 0003-6951 2008 [Refereed][Not invited]
     
    Time resolved images of acoustic waves in the 100 MHz-2.2 GHz range are obtained for an electrically excited thin-film bulk acoustic wave resonator by means of an ultrafast optical technique. Electrical pulses, synchronized to ultrashort laser pulses, piezoelectrically excite the device, and synchronous near-infrared laser pulses interferometrically detect surface motion. The frequency dispersion is extracted using spatiotemporal Fourier transforms, revealing both longitudinal and surface acoustic modes.
  • Wright, O. B., Perrin, B., Matsuda, O., Gusev, V. E.
    Physical Review B 78 (2) 2469-9950 2008 [Refereed][Not invited]
     
    Ultrashort optical pulses are used to excite and interferometrically detect picosecond longitudinal-acoustic pulses in thin films of liquid mercury sandwiched between sapphire plates. We show that the shape of the strain pulses in the mercury can be directly measured through ultrafast changes in optical reflectivity. By analyzing consecutive acoustic echoes, we derive the dispersion of the ultrasonic attenuation and sound velocity for this liquid at frequencies up to 10 GHz. Significant effects of structural relaxation are observed and are compared to a simple model that indicates the presence of picosecond relaxation times in mercury.
  • M. E. Msall, O. B. Wright, O. Matsuda
    12TH INTERNATIONAL CONFERENCE ON PHONON SCATTERING IN CONDENSED MATTER (PHONONS 2007) 92 012026-1 - 4 1742-6588 2007 [Refereed][Not invited]
     
    Picosecond shear acoustic pulses can be generated in solids using ultrashort optical pulses. Here we use this technique to seek high frequency shear waves in water, ethylene glycol and glycerol while simultaneously measuring high frequency longitudinal wave velocity and attenuation. We use a silica thin film on (114) GaAs to generate shear and longitudinal acoustic pulses at frequencies up to similar to 50 GHz by ultrashort pulsed optical excitation. The acoustic pulses are transmitted into adjacent liquids, and are detected through variations in the optical reflectivity. Although we could not detect shear waves in these liquids, we did detect gigahertz longitudinal elastic stiffening.
  • Tomoda, Motonobu, Matsuda, Osamu, Wright, Oliver B., Voti, Roberto Li
    Applied Physics Letters 90 (4) 041114-1 - 3 0003-6951 2007 [Refereed][Not invited]
     
    By means of an ultrafast optical technique, picosecond acoustic strain pulses in a transparent medium are tomographically visualized. The authors reconstruct strain pulses in Au-coated glass from time-domain reflectivity changes as a function of the optical angle of incidence, with similar to 1 ps temporal and similar to 100 nm spatial resolutions. (c) 2007 American Institute of Physics.
  • Matsuda, Osamu, Glorieux, Christ
    Journal of the Acoustical Society of America 121 (6) 3437 - 3445 0001-4966 2007 [Refereed][Not invited]
     
    Acoustic wave propagation in anisotropic media with one-dimensional inhomogeneity is discussed. Using a Green's function approach, the wave equation with inhomogeneous variation of elastic property and mass density is transformed into an integral equation, which is then solved numerically. The method is applied to find the dispersion relation of surface acoustic waves for a medium with continuously or discontinuously varying elastic property and mass density profiles. (c) 2007 Acoustical Society of America.
  • Tournat, V., Profunser, D. M., Muramoto, E., Matsuda, O., Takezaki, T., Sueoka, S., Wright, O. B.
    Physical Review E 74 (2) 026604-1 - 5 1539-3755 2006 [Refereed][Not invited]
     
    The multiple scattering of coherent surface acoustic wave packets in a microstructure is studied using an ultrafast optical technique. By recording a set of acoustic transfer functions, we show that it is possible to implement time-reversal acoustics and refocus the wave packets up to the GHz range, two orders of magnitude higher than usual. Many applications in time-reversal acoustics are thus transposable to correspondingly smaller structures, opening the way to efficient nondestructive characterization and manipulation of multiple scattering on the microscale.
  • Profunser, Dieter M., Wright, Oliver B., Matsuda, O.
    Physical Review Letters 97 (5) 055502-1 - 4 0031-9007 2006 [Refereed][Not invited]
     
    Broadband surface phonon wave packets on a phononic crystal made up of a microstructured line pattern are tracked in two dimensions and in real time with an ultrafast optical technique. The eigenmode distribution and the 2D acoustic band structure are obtained from spatiotemporal Fourier transforms of the data up to 1 GHz. We find stop bands at the zone boundaries for both leaky-longitudinal and Rayleigh waves, and show how the structure of individual acoustic eigenmodes in k space depends on Bloch harmonics and on mode coupling.
  • Hurley, DH, Wright, OB, Matsuda, O, Suzuki, T, Tamura, S, Sugawara, Y
    Physical Review B 73 (12) 125403-1 - 6 1098-0121 2006 [Refereed][Not invited]
     
    Using an optical technique, we present time-resolved measurements of high frequency surface acoustic waves propagating across the boundary between two single crystals. The choice of the elastically anisotropic cubic crystal copper allows the observation of anisotropic surface acoustic propagation with cuspidal wave fronts together with refraction in the presence of significant orientation mismatch. The effect of the subsurface grain boundary angle on the transmitted acoustic field is revealed.
  • Tachizaki, T, Muroya, T, Matsuda, O, Sugawara, Y, Hurley, DH, Wright, OB
    Review of Scientific Instruments 77 (4) 043713-1 - 12 0034-6748 2006 [Refereed][Not invited]
     
    We describe an improved two-dimensional optical scanning technique combined with an ultrafast Sagnac interferometer for delayed-probe imaging of surface wave propagation. We demonstrate the operation of this system, which involves the use of a single focusing objective, by monitoring surface acoustic wave propagation on opaque substrates with picosecond temporal and micron lateral resolutions. An improvement in the lateral resolution by a factor of 3 is achieved in comparison with previous setups for similar samples. (c) 2006 American Institute of Physics.
  • Kashiwada, Saori, Matsuda, Osamu, Baumberg, Jeremy J., Li Voti, Roberto, Wright, Oliver B.
    Journal of Applied Physics 100 (7) 073506-1 - 6 0021-8979 2006 [Refereed][Not invited]
     
    Ultrashort optical pulses are used to excite and probe picosecond acoustic pulses in a sample consisting of an opaque material upon which ice is continuously deposited from the vapor phase at similar to 110 K. By analysis of the ultrasonic propagation and reflection inside the submicron ice film and taking into account the scattering of the probe light by the acoustic waves, the thickness, sound velocity, refractive index, ultrasonic attenuation, and photoelastic constant of the ice film are derived. This method should find applications for the in situ monitoring of thin transparent films during growth. (c) 2006 American Institute of Physics.
  • Dieter M. Profunser, Oliver B. Wright, Osamu Matsuda, Udo Lang, Khelif Abdelkrim, Sarah Benchabane, Vincent Laude
    2006 IEEE ULTRASONICS SYMPOSIUM, VOLS 1-5, PROCEEDINGS 501 - + 1051-0117 2006 [Refereed][Not invited]
     
    Using an ultrafast optical technique, broadband surface acoustic wave packets are tracked on 1D and 2D phononic crystals in two dimensions in real time at frequencies up to similar to 1 GHz. The acoustic band structure is obtained from the data by means of a spatiotemporal Fourier transform. We find stop bands for both leaky longitudinal and Rayleigh waves.
  • Oliver B. Wright, Osamu Matsuda, Yoshihiro Sugawara
    Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 44 (10) 7733  0021-4922 2005/10/11 [Refereed][Not invited]
  • O. Matsuda, T. Tachizaki, T. Fukui, J. J. Baumberg, O. B. Wright
    Physical Review B - Condensed Matter and Materials Physics 71 (11) 1098-0121 2005/03/15 [Refereed][Not invited]
     
    Picosecond acoustic-phonon pulse generation and detection is investigated in a sample containing three GaAs/Al 0.3Ga 0.7As quantum wells of different thickness with an interferometric optical pump and probe technique. The pump photon energy is tuned through the hh1-e1 transitions of each well and the probe photon energy is chosen to allow the detection of the phonon pulses at the sample surface. The phonon pulse shapes are explained with a model that relates the carrier wave functions to the acoustic strain, and the acoustic strain to the detected optical reflectance and phase changes. ©2005 The American Physical Society.
  • Matsuda, O, Aoki, K, Tachizaki, T, Wright, OB
    Journal De Physique Iv 125 361 - 363 1155-4339 2005 [Refereed][Not invited]
     
    Picosecond acoustic pulses generated in solids with ultrashort optical pulses can be detected through the reflectance or phase changes of optical probe pulses. The detection relies on acousto-optic coupling resulting from a combination of the photoelastic effect and transient surface displacements. The acoustic strain pulse shape gives access to the ultrafast dynamics of the electrons that influence the generation process. This pulse shape is directly related to the contribution to the probe light modulation resulting from surface displacement. Here we present a method that allows the discrimination between the photoelastic and surface displacement contributions using a novel oblique optical incidence geometry, allowing the strain pulse shape to be directly obtained in a single measurement.
  • Matsuda, O, Tachizaki, T, Fukui, T, Baumberg, JJ, Wright, OB
    Physical Review B 71 (11) 115330-1 - 13 2469-9950 2005 [Refereed][Not invited]
     
    Picosecond acoustic-phonon pulse generation and detection is investigated in a sample containing three GaAs/Al0.3Ga0.7As quantum wells of different thickness with an interferometric optical pump and probe technique. The pump photon energy is tuned through the hh1-e1 transitions of each well and the probe photon energy is chosen to allow the detection of the phonon pulses at the sample surface. The phonon pulse shapes are explained with a model that relates the carrier wave functions to the acoustic strain, and the acoustic strain to the detected optical reflectance and phase changes.
  • Wright, OB, Matsuda, O, Sugawara, Y
    Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers 44 (6B) 4292 - 4296 0021-4922 2005 [Refereed][Not invited]
  • Tachizaki, T, Matsuda, O, Fukui, T, Baumberg, JJ, Wright, OB
    Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers 44 (6B) 4477 - 4479 0021-4922 2005 [Refereed][Not invited]
     
    High frequency ultrasonic pulse generation and detection are investigated in a sample with three embedded GaAs/Al(0.3)Ga(0.7)As quantum wells by means of ultrashort optical pulses. The experimental results, showing that ultrasonic frequencies up to 0.5THz are detected, are compared with numerical simulations of the ultrasonic pulse generation, propagation and attenuation, and of the optical detection process. The effective optical extinction coefficients of the embedded quantum wells and the ultrasonic attenuation coefficient of Al(0.3)Ga(0.7)As are determined from the analysis.
  • MATSUDA Osamu, WRIGHT Oliver B
    Japanese journal of optics 応用物理学会分科会日本光学会 34 (2) 69 - 74 0389-6625 2005 [Refereed][Not invited]
  • Wright, OB, Matsuda, O, Sugawara, Y
    Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers 44 (10) 7733 - 7733 0021-4922 2005 [Refereed][Not invited]
     
    The use of acoustic pulses to image materials is well-known in echography or sonar applications. We are extending this field by generating point-excited sound pulses on solid surfaces with ultrashort laser pulses and imaging the resulting surface wave propagation in real time. To see the tiny vibrations of the surface, smaller in amplitude than the dimensions of a single atom, we use another set of laser pulses for scanned probing. The typical surface phonon wavelength is of the order of a few microns, corresponding to frequencies up to 1 GHz. With such a system we can watch coherent acoustic wave packets in two dimensions rippling across crystal surfaces and microscopic landscapes.
  • WRIGHT Oliver B, SUGAWARA Yoshihiro, MATSUDA Osamu
    應用物理 応用物理学会 73 (6) 732 - 740 0369-8009 2004/06 [Not refereed][Not invited]
  • Matsuda, O, Wright, OB
    Ultrasonics 42 (1-9) 653 - 656 0041-624X 2004 [Refereed][Not invited]
     
    A theory for the analysis of experiments involving laser picosecond acoustics with obliquely incident probe light in a two-layer structure is outlined. The reflectance and phase changes of the reflected light are calculated with a theory that takes into account the effects of multiple optical reflections. The sample consists of a single partially transparent layer on a substrate, both with arbitrary optical constants. We discuss the conditions in which one may discriminate between components of the optical modulation of a probe beam arising from the photoelastic effect and from the displacement of the sample interfaces induced by the acoustic strain. (C) 2004 Elsevier B.V. All rights reserved.
  • T Tachizaki, O Matsuda, T Fukui, JJ Baumberg, OB Wright
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL. 1, NO. 11 1 (11) 2749 - 2752 1862-6351 2004 [Refereed][Not invited]
     
    Acoustic phonon pulse generation and detection are investigated in a sample with three embedded GaAs/AlGaAs quantum wells by an ultrafast optical pump and probe technique at the temperatures 20 K and 300 K. Scanning the pump photon energies around the hh1-e1 resonances we find a strong variation of the transient reflectance and phase changes. These changes are compared with a numerical simulation based on probe light scattering due to the inhomogeneous photoelastic effect. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • H Yamazaki, O Matsuda, OB Wright, G Amulele
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL. 1, NO. 11 1 (11) 2979 - 2982 1862-6351 2004 [Refereed][Not invited]
     
    Surface phonon wavepackets are generated on aluminium-coated transparent glass balls on irradiation with ultrashort light pulses. Delayed ultrashort probe light pulses are used to image the surface phonon propagation in real time by simply monitoring the modulation in the reflected probe beam intensity caused by the photoelastic effect. Imaging was achieved in the region of the phonon source and at the opposite pole of the sphere. (C) 2004 WILEY-VCH Verlag GmbH & Co. MaA, Weinheim.
  • Tournat, V, OB Wright, O Matsuda
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL. 1, NO. 11 1 (11) 2737 - 2740 1862-6351 2004 [Refereed][Not invited]
     
    We describe a means to achieve time reversal acoustics on nanosecond or picosecond time scales for surface or bulk longitudinal phonon modes, respectively, by the use of ultrashort optical pulses for the phonon generation. After the presentation of the theory of low and high frequency time reversal acoustics, the limitations of the method and possible experiments on nanostructures and microstructures are discussed. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • H Yamazaki, O Matsuda, OB Wright
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL. 1, NO. 11 1 (11) 2991 - 2994 1862-6351 2004 [Refereed][Not invited]
     
    Surface phonon imaging is very useful for testing thin structures, in particular because it allows film thicknesses or elastic constants to be derived. We present a method for imaging surface phonons based on optical reflectivity measurements combined with excitation using picosecond optical pulses. Surface phonons are generated in a thin aluminium. film on a transparent glass substrate. The induced strain modulates the refractive index of the film and substrate through the photoelastic effect. Probe laser pulses incident from the film or substrate side can be used to image surface phonon propagation in real time by simply monitoring the modulation in the reflected probe beam intensity. When we image from the substrate side, surface-skimming longitudinal bulk phonons are clearly imaged in addition to the surface phonons. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Matsuda, O, Wright, OB, Hurley, DH, Gusev, VE, Shimizu, K
    Physical Review Letters 93 (9) 095501-1 - 4 0031-9007 2004 [Refereed][Not invited]
     
    Using an optical technique we generate and detect picosecond shear and quasishear coherent acoustic phonon pulses in the time domain. Thermoelastic and piezoelectric generation are directly achieved by breaking the sample lateral symmetry using crystalline anisotropy. We demonstrate efficient detection in isotropic and anisotropic media with various optical incidence geometries.
  • Takehiro Tachizaki, Osamu Matsuda, Takashi Fukui, Jeremy J. Baumberg, Oliver B. Wright
    Physica Status Solidi C: Conferences 1 (11) 2749 - 2752 1610-1634 2004 [Refereed][Not invited]
     
    Acoustic phonon pulse generation and detection are investigated in a sample with three embedded GaAs/AlGaAs quantum wells by an ultrafast optical pump and probe technique at the temperatures 20 K and 300 K. Scanning the pump photon energies around the hh1-e1 resonances we find a strong variation of the transient reflectance and phase changes. These changes are compared with a numerical simulation based on probe light scattering due to the inhomogeneous photoelastic effect. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Hiroto Yamazaki, Osamu Matsuda, Oliver B. Wright
    Physica Status Solidi C: Conferences 1 (11) 2991 - 2994 1610-1634 2004 [Refereed][Not invited]
     
    Surface phonon imaging is very useful for testing thin structures, in particular because it allows film thicknesses or elastic constants to be derived. We present a method for imaging surface phonons based on optical reflectivity measurements combined with excitation using picosecond optical pulses. Surface phonons are generated in a thin aluminium film on a transparent glass substrate. The induced strain modulates the refractive index of the film and substrate through the photoelastic effect. Probe laser pulses incident from the film or substrate side can be used to image surface phonon propagation in real time by simply monitoring the modulation in the reflected probe beam intensity. When we image from the substrate side, surface-skimming longitudinal bulk phonons are clearly imaged in addition to the surface phonons. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.
  • Vincent Tournat, Oliver B. Wright, Osamu Matsuda
    Physica Status Solidi C: Conferences 1 (11) 2737 - 2740 1610-1634 2004 [Refereed][Not invited]
     
    We describe a means to achieve time reversal acoustics on nanosecond or picosecond time scales for surface or bulk longitudinal phonon modes, respectively, by the use of ultrashort optical pulses for the phonon generation. After the presentation of the theory of low and high frequency time reversal acoustics, the limitations of the method and possible experiments on nanostructures and microstructures are discussed. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • T. Saito, O. Matsuda, O. B. Wright
    Physical Review B - Condensed Matter and Materials Physics 67 (20) 1550-235X 2003/05/28 [Refereed][Not invited]
     
    The generation mechanisms for picosecond acoustic phonon pulses excited by ultrashort optical pulses in metals with strong electron-phonon coupling are elucidated. By means of an interferometric probing technique to extract changes in optical phase and amplitude, the acoustic pulse shapes in the transition metals Ni and Cr are shown to be governed by both thermal and nonequilibrium electron diffusion. Quantitative comparison of the results with a model that takes into account the nonequilibrium electron dynamics and ultrasonic attenuation gives excellent agreement. © 2003 The American Physical Society.
  • Sugawara, Y, Wright, OB, Matsuda, O
    Applied Physics Letters 83 (7) 1340 - 1342 0003-6951 2003 [Refereed][Not invited]
     
    We present a method based on a combination of temporal and spatial Fourier image analysis, involving the incorporation of a time-reversed acoustic propagation component, that can be used to obtain the angular dispersion or general dispersion relations of multiple surface acoustic modes excited by a localized pulsed source. The method is applied to the study of acoustic propagation at the surface of the highly anisotropic single-crystal TeO2 coated with a thin gold film. (C) 2003 American Institute of Physics.
  • Matsuda, O, Wright, OB
    Review of Scientific Instruments 74 (1) 895 - 897 0034-6748 2003 [Refereed][Not invited]
     
    Laser picosecond acoustics involves the excitation and detection of picosecond acoustic strain pulses in thin films with ultrashort light pulses. The use of oblique probe light incidence permits a greater degree of freedom in choosing the optical probing conditions and thereby should allow the extraction of more information about the profile of the propagating acoustic strain pulses. Here, we present a theory for the modulation of light reflected at oblique incidence from a solid containing an acoustic strain distribution. The theory can account for the real and imaginary parts of the reflectance variation, and involves both the effect of the transient surface motion and of the photoelastically modulated dielectric constants in the solid. We show, in particular, how the theory can be applied to extract the contribution to the reflectance change arising from the surface motion in an opaque isotropic solid, thereby allowing direct access to the shape of the acoustic strain pulse propagating therein. (C) 2003 American Institute of Physics.
  • Hirori, H, Tachizaki, T, Matsuda, O, Wright, OB
    Physical Review B 68 (11) 113102-1 - 4 2469-9950 2003 [Refereed][Not invited]
     
    Electron excitation and relaxation in chromium are probed with 20-fs time resolution using an ultrafast optical technique. We obtain good fits to the data for the transient reflectivity and transmittivity changes in a thin film using a simple model of electron relaxation, suggesting the existence of an efficient electron-electron thermalization process on ultrashort-time scales. Quantitative analysis allows the extraction of thermo-optic coefficients and dielectric constant variations related to both the electron and the lattice temperatures.
  • Sugawara, Y, Wright, OB, Matsuda, O
    Review of Scientific Instruments 74 (1) 519 - 522 0034-6748 2003 [Refereed][Not invited]
     
    We present a real-time imaging technique for surface acoustic waves on samples with opaque substrates. We image the surface acoustic wave propagation on a silicon substrate coated with a gold film, and derive the dispersion relation for propagation in symmetry directions. In addition, we image surface acoustic waves at frequencies up to 2 GHz on a diamond substrate coated with a gold film, and on a microstructure deposited on a silicon substrate. (C) 2003 American Institute of Physics.
  • Saito, T, Matsuda, O, Wright, OB
    Physical Review B 67 (20) 205421-1 - 7 2469-9950 2003 [Refereed][Not invited]
     
    The generation mechanisms for picosecond acoustic phonon pulses excited by ultrashort optical pulses in metals with strong electron-phonon coupling are elucidated. By means of an interferometric probing technique to extract changes in optical phase and amplitude, the acoustic pulse shapes in the transition metals Ni and Cr are shown to be governed by both thermal and nonequilibrium electron diffusion. Quantitative comparison of the results with a model that takes into account the nonequilibrium electron dynamics and ultrasonic attenuation gives excellent agreement.
  • H. Hirori, T. Tachizaki, O. Matsuda, O. B. Wright
    Physical Review B - Condensed Matter and Materials Physics 68 (11) 1131021 - 1131024 0163-1829 2003 [Refereed][Not invited]
     
    Electron excitation and relaxation in chromium are probed with 20-fs time resolution using an ultrafast optical technique. We obtain good fits to the data for the transient reflectivity and transmittivity changes in a thin film using a simple model of electron relaxation, suggesting the existence of an efficient electron-electron thermalization process on ultrashort-time scales. Quantitative analysis allows the extraction of thermo-optic coefficients and dielectric constant variations related to both the electron and the lattice temperatures.
  • 松田 理, 寺田 卓哉, 稲垣 克彦
    超音波techno 日本工業出版 15 (1) 51 - 54 0916-2410 2003/01 [Not refereed][Not invited]
  • 菅原 美博, Wright Oliver B, 松田 理
    超音波techno 日本工業出版 15 (1) 47 - 50 0916-2410 2003/01 [Not refereed][Not invited]
  • Yoshihiro Sugawara, Oliver B. Wright, Osamu Matsuda
    Optics and Photonics News 13 (12) 20  2002/12 [Not refereed][Not invited]
  • Matsuda, O, Ishii, I, Fukui, T, Baumberg, JJ, Wright, OB
    Physica B-Condensed Matter 316 205 - 208 0921-4526 2002 [Refereed][Not invited]
     
    Ultrashort coherent phonon-pulse generation and detection is investigated in a GaAs-Al0.3Ga0.7As quantum well structure containing three wells of different widths using an optical pump and probe method. The pump photon energy is tuned to the region of the hhl-el transition energies of the wells and the probe photon energy is chosen for detection of the phonon pulses that reach the sample surface. By studying the dependence of the probe reflectance change on the pump photon energy, we demonstrate the possibility of wavelength-selective excitation of picosecond acoustic-phonon pulses in quantum wells. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Sugawara, Y, Wright, OB, Matsuda, O, Gusev, VE
    Ultrasonics 40 (1-8) 55 - 59 0041-624X 2002 [Refereed][Not invited]
     
    We demonstrate a new method for a real-time imaging of surface acoustic waves at frequencies up to 1 GHz with picosecond temporal and micron spatial resolutions using an ultrafast optical pump and probe technique combined with a common path interferometer. Using samples with isotropic or anisotropic substrates coated with metallic thin films, we observe the propagation of Rayleigh-like modes and surface-skimming bulk modes as well as resolving surface phonon focusing effects. In addition we image surface acoustic wave propagation in a laterally inhomogeneous sample. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Sugawara, Y, Wright, OB, Matsuda, O, Takigahira, M, Tanaka, Y, Tamura, S, Gusev, VE
    Physical Review Letters 88 (18) 185504-1 - 4 0031-9007 2002 [Refereed][Not invited]
     
    We present a new method for imaging surface phonon focusing and dispersion at frequencies up to 1 GHz that makes use of ultrafast optical excitation and detection. Animations of coherent surface phonon wave packets emanating from a point source on isotropic and anisotropic solids are obtained with micron lateral resolution. We resolve rounded-square shaped wave fronts on the (100) plane of LiF and discover isolated pockets of pseudosurface wave propagation with exceptionally high group velocity in the (001) plane of TeO2 . Surface phonon refraction and concentration in a minute gold pyramid is also revealed.
  • Wright, OB, Sugawara, Y, Matsuda, O, Takigahira, M, Tanaka, Y, Tamura, S, Gesev, VE
    Physica B-Condensed Matter 316 29 - 34 0921-4526 2002 [Refereed][Not invited]
     
    Surface phonon propagation in anisotropic thin film structures displays beautiful and complex wavefronts. Using an interferometric optical pump and probe technique, we have imaged the propagation of surface phonons at frequencies up to 1 GHz in real time, allowing 'movies' of their wavefronts to be made with picosecond temporal and micron spatial resolutions. We image the propagation on various isotropic and anisotropic thin film structures, and give examples of how the dispersion relation can be directly derived from such movies. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Wright, OB
    Ultrasonics 40 (1-8) 753 - 756 0041-624X 2002 [Refereed][Not invited]
     
    The field of laser picosecond acoustics has thrived owing to the ease of detection of propagating picosecond acoustic pulses through changes in optical reflectance. Reflectance changes are caused by the inhomogeneous modulation of the refractive index by the propagating elastic strain through the photoelastic effect and also by the associated induced motion of the surface and interfaces. In this paper we present a general formula for calculating the reflectance change based on a rigorous one-dimensional treatment of the perturbation in optical properties of arbitrary multilayer structures, The theory is applied to the quantitative analysis of data obtained by laser picosecond acoustics for a SiO2-Cr double-layer film on a fused silica substrate. The analysis allows the discrimination of the photoelastic contribution and the surface or interface motion contribution to the experimental reflectance variation. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Terada, T, Inagaki, K, Wright, OB
    Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 41 (5B) 3545 - 3546 0021-4922 2002 [Refereed][Not invited]
     
    Ultrasonic force microscopy allows the local mapping of elasticity in atomic force microscopy by the application of ultrasonic vibration to the cantilever or sample. In an attempt to analyse the results of ultrasonic force microscopy in a quantitative fashion, a force-distance curve measurement is done with ultrasonic vibration applied to the cantilever base, and the results are compared with a model of the cantilever dynamics and tip-sample interaction based on the finite-difference technique.
  • Saito, T, Matsuda, O, Wright, OB
    Physica B-Condensed Matter 316 304 - 307 0921-4526 2002 [Refereed][Not invited]
     
    The generation mechanisms for longitudinal acoustic-phonon pulses excited in the transition metal chromium with sub-picosecond optical pulses are studied. The temporal and spatial evolution of the electron and lattice temperatures up to several picoseconds after laser photon absorption have a major impact on the final profile of the acoustic-phonon pulses. These phonon pulse shapes can be explained by considering both thermal and electron diffusion, and taking into account the effects of frequency-dependent ultrasonic attenuation. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Wright, OB
    Journal of the Optical Society of America B-Optical Physics 19 (12) 3028 - 3041 0740-3224 2002 [Refereed][Not invited]
     
    We derive analytical formulas for the modulation of the reflectance and transmittance of light normally incident on a multilayer thin-film structure whose refractive indices are perturbed by an ultrashort optical pulse. The formulas, expressed in compact form, should prove useful for analysis of a wide range of ultrashort time-scale experiments on multilayers as well as longer time-scale photoacoustic and photothermal experiments based on optical probing. We demonstrate our method by the analysis of the modulated reflectance variation of a SiO2/Cr structure in which picosecond acoustic pulses have been optically excited. (C) 2002 Optical Society of America.
  • Inagaki, K, Matsuda, O, Wright, OB
    Applied Physics Letters 80 (13) 2386 - 2388 0003-6951 2002 [Refereed][Not invited]
     
    We propose a technique based on ultrasonic force microscopy that exploits the hysteresis in cantilever jumping to and from a sample while varying the ultrasonic amplitude. Both the elastic modulus and the work of adhesion can be determined by comparision with a relation derived between their ratio and the cantilever shift at the jump-in point. The method is applied to measurements on an aluminum thin film. (C) 2002 American Institute of Physics.
  • Wright, OB, Li Voti, R, Matsuda, O, Larciprete, MC, Sibilia, C, Bertolotti, M
    Journal of Applied Physics 91 (8) 5002 - 5009 0021-8979 2002 [Refereed][Not invited]
     
    The problem of the photothermal modulation of optical beams passing through multilayer films is an extremely complex one owing to the inhomogeneously modulated refractive index combined with multiple optical reflections inside the sample. This problem has so far not been given an exact analytical treatment in the field of photothermal probing. We consider here such a treatment for normal-incidence optical probing in reflectance of photothermally modulated single-layer thin-film samples with arbitrary optical constants. The validity of the method is demonstrated by application to a thin transparent film of silica on a silicon substrate. (C) 2002 American Institute of Physics.
  • Matsuda, O, Wright, OB
    Analytical Sciences 17 S216 - S218 0910-6340 2001 [Refereed][Not invited]
     
    The principles of the photo-detection of shear acoustic waves in laser picosecond acoustics are discussed. The shear strain in an isotropic material induces off-diagonal components in the dielectric tensor, that is, the material shows strain induced birefringence. By considering the light reflection from the surface of a birefringent material, it is proved that one needs 1) non-normal incidence of probe light, 2) a shear direction perpendicular to the plane of incidence, and 3) both S and P polarization components of the probe light, for efficient shear strain detection.
  • Wright, OB, Perrin, B, Matsuda, O, Gusev, VE
    Physical Review B 64 (8) 081202-1 - 4 2469-9950 2001 [Refereed][Not invited]
     
    We describe an experimental investigation of the generation and detection of picosecond acoustic-phonon pulses in a thin slab of GaAs using ultrashort optical pulses. Comparison of the optical phase variation with a simple theory for ambipolar diffusion indicates that carrier diffusion has a significant effect on the shape of the phonon pulses generated. The phonon pulse duration is measured to be similar to 25 ps, four times longer than that expected from optical-absorption considerations alone, indicating that hot carriers penetrate more than 100 nm into the sample during the phonon pulse generation process.
  • O. B. Wright, O. Matsuda, B. Perrin, V. E. Gusev
    Physical Review B - Condensed Matter and Materials Physics 64 (8) 1550-235X 2001 [Refereed][Not invited]
     
    We describe an experimental investigation of the generation and detection of picosecond acoustic-phonon pulses in a thin slab of GaAs using ultrashort optical pulses. Comparison of the optical phase variation with a simple theory for ambipolar diffusion indicates that carrier diffusion has a significant effect on the shape of the phonon pulses generated. The phonon pulse duration is measured to be ∼25 ps, four times longer than that expected from optical-absorption considerations alone, indicating that hot carriers penetrate more than 100 nm into the sample during the phonon pulse generation process. © 2001 The American Physical Society.
  • Y Wang, T Nakaoka, M Nakamura, O Matsuda, K Murase
    PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 228 - 229 0930-8989 2001 [Refereed][Not invited]
     
    GexSe1-x glasses have been investigated by Raman scattering. The ability of crystallization is obtained by studies of heating glasses from room temperature up to 1000 K. To understand the low-frequency dynamics of the network, we propose a fractal-structure view and a qualitative degree of the fragility. Transition with the connectivity for each studied property is universally related to the stiffness transition, derived from the concept of the constraint theory.
  • T Nakaoka, Y Wang, O Matsuda, K Inoue, K Murase
    PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 1687 - 1688 0930-8989 2001 [Refereed][Not invited]
     
    We have investigated the structural relaxations by Raman scattering (10-350 cm(-1)) in GexSe1-x glasses (0.07 less than or equal to x less than or equal to 0.35). Around and above the glass transition temperature, strong quasielastic scattering is observed in the low-frequency spectra (10-90 cm(-1)) of floppy glasses (x less than or equal to 0.20). On the other hand, in rigid glasses (x greater than or equal to 0.23), the strong quasielastic contribution cannot be detected in our spectra. We discuss the transition of the relaxational dynamics from floppy glasses to rigid ones in terms of the constraint counting theory. The distinctness of the transition demonstrates a self-organization of the network.
  • OB Wright, B Perrin, O Matsuda, VE Gusev
    PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 192 - 193 0930-8989 2001 [Refereed][Not invited]
     
    Femtosecond spectroscopy of semiconductors has been extensively studied because it provides a window for the observation of ultrafast carrier distributions. Here we report an experimental investigation of the ultrafast coherent acoustic phonon generation mechanisms in bulk GaAs with ultrashort optical pulses. Comparison with a simple theory for ambipolar diffusion indicates that carrier diffusion has a significant effect on the spectrum of the phonon pulses generated.
  • Ishii, I, O Matsuda, T Fukui, JJ Baumberg, OB Wright
    PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 871 - 872 0930-8989 2001 [Refereed][Not invited]
     
    Coherent acoustic phonon pulses are excited and detected in a GaAs/Al-0.3 Ga-0.7 As double quantum well structure using femtosecond optical Pulses, The wavelength of the infrared pump light is chosen to selectively generate picosecond acoustic phonon pulses in two buried quantum wells. The wavelength of the probe light pulses is chosen to allow phonon pulse detection in the near-surface region of the sample. Using an interferometric detection technique both reflectivity and phase variations of the probe beam are monitored, an the phonon pulses generated in the well regions are clearly observed in both these variations. An excellent agreement is obtained when the data is compared to a model accounting for the transient surface displacement combined with the spatially distributed variations in refractive index.
  • T Nakaoka, Y Wang, O Matsuda, K Inoue, K Murase
    PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 113 - 114 0930-8989 2001 [Refereed][Not invited]
     
    We have observed resonant Raman enhancement of stretching vibration of Se-Se bonds relative to breathing vibration of GeSe4/2 tetrahedra at room temperature and 15 K in GeSe2 chalcogenide semiconducting glass. At 15 K, structural changes by illumination, which cause photodarkening, induce excess resonant enhancement. After the structural changes are saturated, we can observe a reversible change with the excitation power in resonant Raman spectra. It is found that the origin of the the reversible power dependence is the same as that of the excess resonant enhancement. Both of them are attributed to three-fold coordinated Se atoms forming Se-Se bonds, which cause the photodarkening.
  • T Nakaoka, Y Wang, K Murase, O Matsuda, K Inoue
    PHYSICAL REVIEW B 61 (23) 15569 - 15572 1098-0121 2000/06 [Refereed][Not invited]
     
    The relationship between the local structures and the electronic stares of layered crystalline GeSe2 are studied by resonant Raman scattering. We observe 34 Raman-active modes of symmetry A(g), and find a selective resonant enhancement of the modes. Almost all the modes are enhanced around 2.7 eV except the two modes. This selective enhancement is attributed to the resonant effect with the localized exciton. We find the essential difference in the atomic motions between the resonant and nonresonant modes. Such behaviors are explained by a structural model of the localized exciton.
  • Wang, Y, Komamine, T, Nakaoka, T, Matsuda, O, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 266 (Pt.B) 904 - 907 0022-3093 2000 [Refereed][Not invited]
     
    We have investigated the effect of thermal annealing on dynamics of photoluminescence (PL) in vacuum-evaporated a-GeSe2 films with thickness of 15 mu m. The intensity of PL increases over 200 times after annealing at 250 degrees C, which makes it possible to take a first investigation on both decay time and fatigue effect. The disordered amorphous structure of the a-GeSe2 film, containing wrong bonds, Ge-Ge and Se-Se, has been reconstructed to a stable structure by diminishing the number of the wrong bonds and the related strain or internal pressure by thermal annealing. (C) 2000 Elsevier Science B.V. All rights reserved.
  • Nakaoka, T, Wang, Y, Matsuda, O, Inoue, K, Murase, K
    Journal of Luminescence 87-9 617 - 619 0022-2313 2000 [Refereed][Not invited]
     
    Relaxation processes of the photoexcited states in layered crystalline GeSe2 are studied by time-resolved photoluminescence measurement. Two photoluminescence bands, P1 and P2, are clearly resolved from their decay kinetics. It is found that one of the relaxation pathways to the P2 band arises from a band-edge exciton state. The P2 band shows no polarization dependence, in spite of the fact that the photoexcitation of the exciton shows a strongly anisotropic optical character, We discuss the relaxation process on the basis of the luminescence characteristics and the structural model of the band-edge exciton quasi-localized at edge-sharing tetrahedra, (C) 2000 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Yamagata, K, Saitoh, Y, Wang, Y, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 266 (Pt.B) 908 - 912 0022-3093 2000 [Refereed][Not invited]
     
    The intensity and decay profile of the photoluminescence (PL) in grassy GeSe2 are measured as a function of temperature from 7 to 200 K. The intensity decreases exponentially in the temperature region >100 K. The complicated temperature dependence of the decay profile as well as the dependence of the intensity are explained in a unified framework by adopting a model of the luminescent sites whose thermal activation energy for the non-radiative process is distributed. We show that the intensity variation is affected by the non-radiative process while the decay life time depends almost only on the radiative transition rate. (C) 2000 Elsevier Science B.V. All rights reserved.
  • Wang, Y, Nakamura, M, Matsuda, O, Murase, K
    Journal of Non-Crystalline Solids 266 (Pt.B) 872 - 875 0022-3093 2000 [Refereed][Not invited]
     
    We have investigated the Raman spectra in a range 3-100 cm(-1) in chalcogenide glasses, GexS1-x and GexSe1-x, with 0 less than or equal to x less than or equal to 0.42 in the average coordination number, [r], from 2 to 2.84. The relation between the rigidity percolation, based on the prediction of the mean-held constraint theory, and a relative degree of fragility, representing the structural relaxation of the network, are demonstrated by varying the structures of the glasses. The obtained fragility of the glasses for x < 0.20 ([r] < 2.4) is larger than that for x > 0.20. A decrease of the fragility at about [r] = 2.4 is attributed to the predicted rigidity percolation threshold where the glass changes from floppy to rigid, and mesoscopic structural changes beyond the mean-field theory. For [r] > 2.4, fragility depends on chemical bonds between Ge-Se and Ge-S systems, since the local structure directly contributes to the properties of the overcoordinated network. (C) 2000 Elsevier Science B.V. All rights reserved.
  • Hurley, DH, Wright, OB, Matsuda, O, Gusev, VE, Kolosov, OV
    Ultrasonics 38 (1-8) 470 - 474 0041-624X 2000 [Refereed][Not invited]
     
    We present experimental results concerning the laser generation of picosecond acoustic pulses and their propagation in isotropic and anisotropic materials. We make use of a conventional reflectance detection technique as well as interferometric detection to probe the real and imaginary changes in reflectance. We also demonstrate the detection of transverse acoustic waves by mode conversion at an interface between an isotropic polycrystalline film and an anisotropic substrate, (C) 2000 Elsevier Science B.V. All rights reserved.
  • Nakaoka, T, Wang, Y, Murase, K, Matsuda, O, Inoue, K
    Physical Review B 61 (23) 15569 - 15572 0163-1829 2000 [Refereed][Not invited]
  • Wang, Y, Matsuda, O, Serikawa, T, Murase, K
    Journal De Physique Iv 10 (P7) 259 - 262 1155-4339 2000 [Refereed][Not invited]
     
    To clarify the structure of amorphous silicon (a-Si), with the thickness less than 5nm, affected by the interface between a-Si and a-SiO2 as well as the structural changes after an annealing of 900 degrees C in N-2 gas atmosphere, Raman scattering investigation is carried out in a-Si/SiO2 superlattice (SL) films prepared by the sputtering method. Vibrational motion of strained a-Si at and near a-Si/SiO2 interface is influenced by the vibration of pressed a-SiO2 at the other side of the interface that results a blue shift of transverse optic (TO) -like modes in a-Si. The narrow space of thin (<2.5 nm in this work) a-Si layer impedes the crystallization to a-Si and the relaxation of energy during the crystallization event.
  • Nakamura, M, Matsuda, O, Wang, Y, Murase, K
    Physica B 263 330 - 332 0921-4526 1999 [Refereed][Not invited]
     
    We have measured low frequency Raman spectra in Ge chalcogenide glasses. The dependence of spectral dimensionality of stretching fracton, (d) over tilde(s), on the sample composition is obtained from low frequency reduced Raman spectrum and is correctly correlated to the actual network dimensionality of Ge chalcogenide glasses. The value of (d) over tilde(s) is supposed to be a parameter representing the degree of localization of lattice vibrations and an indicator of network dimensionality of network glasses. The findings on the interpretation of (d) over tilde(s) should be applied in future research of disordered systems. (C) 1999 Elsevier Science B.V. All rights reserved.
  • Wang, Y, Nakamura, M, Matsuda, O, Murase, K
    Physica B 263 313 - 316 0921-4526 1999 [Refereed][Not invited]
     
    We have investigated low-frequency Raman spectra of glassy GexSe1-x (x = 0-0.40) in a range of 3-100 cm(-1) A relative degree of fragility was first obtained in the Ge-Se system by an investigation of the line shape of low-frequency Raman spectra. The results imply an important relationship between the changes of fragility and the structural changes. The rapid drop of the fragility at average coordination number, [r], of 2.4 (x = 2.0) is considered as evidence for the rigidity threshold predicted by the mean-field constraint counting procedures. (C) 1999 Elsevier Science B.V. All rights reserved.
  • Hanzawa, H, Kobayashi, M, Matsuda, O, Murase, K, Giriat, W
    Physica Status Solidi a-Applied Research 175 (2) 715 - 724 0031-8965 1999 [Refereed][Not invited]
     
    The temperature dependence of photoluminescence spectra in Mn-doped ZnS retrieved after the pressure-induced structural phase transition has been studied in the energy range from 0.8 to 2.5 eV. At room temperature, strong photoluminescence with the peak energy of 1.3 eV has been observed, This luminescence band is similar to the near infrared emission band observed in virgin bulk crystals with relatively large Mn concentration. However, the luminescence intensity is much stronger than that in the bulk crystals. The temperature dependence has revealed that the large quantum efficiency at room temperature resulted from the suppression of thermal quenching. At low temperature, the yellow band at 2.1 eV which is caused by the internal transition within the Mn2+ ions and the emission band at 1.6 eV are also observed in the pressure-retrieved samples. In the bulk crystal, a new emission band has been observed near 0.9 eV. The effective phonon energy and the Huang-Rhys factor of these spectra are determined using a configuration coordinate model.
  • Nakamura, M, Matsuda, O, Murase, K
    Physical Review B 57 (17) 10228 - 10231 0163-1829 1998/05 [Refereed][Not invited]
  • Wang, Y, Matsuda, O, Inoue, K, Yamamuro, O, Matsuo, T, Murase, K
    Journal of Non-Crystalline Solids 232 702 - 707 0022-3093 1998 [Refereed][Not invited]
     
    The structures of glassy and liquid GexSe1-x (0.00 less than or equal to x less than or equal to 0.33) and the structural changes occurring at the glass-transition have been investigated, using Raman scattering combined with differential scanning calorimetry. The medium range structures in the glassy and liquid states are discussed in relation to anomalous changes in the Raman spectra at the glass-transition. The characteristic spectrum of crystalline GeSe2 appears, superimposed on that for liquid GexSe1-x, in the composition range 0.18 less than or equal to x less than or equal to 0.33. It is found that the rate of recrystallization shows an abrupt change when x increases from 0.15 to 0.18? although the structure does not change significantly. These results are considered as evidence for a rigidity threshold at an average coordination, [r], of 2.4 (x = 0.20), which is predicted based on mean-field constraint counting procedures. (C) 1998 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Saitoh, Y, Yamagata, K, Wada, Y, Wang, Y, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 227 (Pt.B) 829 - 832 0022-3093 1998 [Refereed][Not invited]
     
    Time-resolved photoluminescence measurement is done on glassy GeSe2. The decay curve consists of a process whose decay time is about similar to 0.3 ms and a faster process whose decay time is less than 1 mu s. The decay time of the slower process becomes short with increasing excitation energy. The ratio between the slower process and the faster process increases with increasing excitation energy especially in the higher emission energy region. The relaxation process from the excited state just after the photon absorption to the trapped excited state is discussed. (C) 1998 Elsevier Science B.V. AII rights reserved.
  • Wang, Y, Matsuda, O, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 227 (Pt.B) 728 - 731 0022-3093 1998 [Refereed][Not invited]
     
    The structural difference, due to different preparation methods, in glassy GeSe2 samples is investigated by photo-induced crystallization phenomena using time-resolved Raman measurement. Crystallization temperatures of two samples, which were cooled from melts at different cooling rates, were almost the same in thermal crystallization processes. However, in photo-induced crystallization processes, threshold temperatures of the crystallization directly depended on their cooling rates, the smaller cooling rate the lower the threshold temperature. In the sample cooled at a smaller cooling rate, its medium-range structure is more similar to crystalline nuclei, or easier to transform into crystalline nuclei. (C) 1998 Elsevier Science B.V. All rights reserved.
  • Matsuda, O, Takeuchi, H, Wang, Y, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 232 554 - 559 0022-3093 1998 [Refereed][Not invited]
     
    The photo-induced and thermal crystallization processes of amorphous GeSe2 films are studied and compared by observation of Raman scattering spectra, Reversible changes of medium range structure are observed in a temperature region well below the crystallization temperature in the thermal crystallization process. This structure is assumed to be caused by large structural fluctuations in the evaporated films. On the other hand, in the photo-induced crystallization process, structural changes are not observed before crystallization begins. The observation is consistent with the fact that the high temperature phase crystal grows much more favorably than the low temperature phase crystal does in the photo-induced crystallization process, though the crystallization temperature is well below the thermal crystallization temperature in the dark. (C) 1995 Elsevier Science B.V. All rights reserved.
  • Takeuchi, H, Matsuda, O, Murase, K
    Journal of Non-Crystalline Solids 238 (1-2) 91 - 97 0022-3093 1998 [Refereed][Not invited]
     
    The Raman scattering properties at high temperatures in non-crystalline Ge30Se70 prepared by melt-quenching (MQ) and vacuum evaporation (VE) are investigated from the view point of the structural difference between them. In the VE film with increasing temperatures, the mesoscopic structure containing edge-sharing GeSe4/2 tetrahedra changes to the structure only containing the corner-sharing tetrahedra even at temperatures well below the glass transition temperature. In the MQ-glass, the structure containing edge-sharing tetrahedra is more stable than that in the VE-film. (C) 1998 Elsevier Science B.V. All rights reserved.
  • Nakamura, M, Matsuda, O, Murase, K
    Physical Review B 57 (17) 10228 - 10231 1098-0121 1998 [Refereed][Not invited]
     
    Low-frequency Raman spectra (10 (Formula presented)-80 (Formula presented) have been studied in the (Formula presented) glasses. The Raman spectra reduced by the Bose factor (Formula presented), which are proportional to the vibrational density of states, show a power-law dependence of the frequency, (Formula presented), (Formula presented) in a low-frequency region. The value (Formula presented) is a noninteger, which suggests that these glassy systems have fractal structures. The spectra (Formula presented) of Se-rich samples are classified into three regions whose vibrational properties are due to acoustic phonons, bending fractons, and stretching fractons, whereas that of the Ge-rich samples’ two regions are due to acoustic phonons and stretching fractons. The difference of two types of these low-frequency properties are explained by correlation of the structural crossover length (Formula presented) and the elastic crossover length (Formula presented) The threshold of these phenomena occurs near (Formula presented), which may be related to the prediction of the Phillips-Thorpe constraint theory. © 1998 The American Physical Society.
  • Yanagisawa, J, Nakayama, H, Matsuda, O, Murase, K, Gamo, K
    Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms 127 893 - 896 0168-583X 1997 [Refereed][Not invited]
     
    Ion beam deposition using low-energy (100 eV) Si2+ focused ion beams (FIB) was performed on gold evaporated substrate at room temperature under various deposition conditions, such as beam scan rates of the FIB and background oxygen pressures of the sample chamber during the deposition. From Auger electron spectroscopy (AES) measurement, it was found that the amount of the oxygen incorporated inside the film can be controlled by the deposition ambient. From the chemical shift in AES spectra and Raman spectroscopy, it was found that deposited Si without oxygen ambient was amorphous and the observed oxygen in the film deposited in high oxygen ambient was chemically bonded with silicon and formed silicon-oxygen bonds,
  • Wang, Y, Matsuda, O, Inoue, K, Murase, K
    Progress of Theoretical Physics Supplement 126 (126) 191 - 194 0375-9687 1997 [Refereed][Not invited]
     
    The glass-transition, crystallization and melting in GexSe1-x (0 less than or equal to x less than or equal to 0.33) have been studied by Raman scattering. Raman spectra exhibit some anomalous changes at the glass-transition. On the basis of these anomalous features which relate to the structural changes, we investigate a medium range structure in glassy and liquid GexSe1-x. In the Ge composition range of 0.04 < x < 0.18, both GeSe2 and Se crystals are much more difficult to be obtained than in the other Ge composition.
  • Wang, Y, Nakamura, M, Matsuda, O, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 198 (Pt 2) 753 - 757 0022-3093 1996 [Refereed][Not invited]
     
    We have investigated the dynamical processes of glass transition, crystallization and melting in GeSe2 by analyzing Raman spectra of glassy, crystalline and liquid GeSe2 as a function of temperature in a range between room temperature and 730 degrees C. Raman vibration bands related to short- and medium-range structures are observed in glassy and liquid forms. The result suggests that there is a topologically crystalline layer-like fragments in these two forms. The change of the spectral shape around the glass-transition temperature is explained by the decrease of interlayer interaction between the neighboring layer-like fragments consistent with the decrease of the viscosity.
  • Matsuda, O, Ohba, T, Murase, K, Ono, I, Grekos, P, Kouchi, T, Nakatake, M, Tamura, M, Namatame, H, Hosokawa, S, Taniguchi, M
    Journal of Non-Crystalline Solids 198 (Pt 2) 688 - 691 0022-3093 1996 [Refereed][Not invited]
     
    The density of states in the conduction band as well as that in the valence band in amorphous Ge20Si80-xBix and Bi2Se3 thin films has been investigated by inverse-photoemission and ultraviolet photoemission spectroscopies. We have found that, with increasing Bi content, the conduction band minimum approaches the Fermi level, while the valence band maximum remains unchanged with respect to the Fermi level, It is concluded that the mixture of Ge-Se and Bi-Se anti-bonding orbits compose the conduction band of the Ge-Se-Bi system. The origin of the n-type conduction in the high Bi concentration region of Ge20Se80-xBix is attributed to this conduction band which appears just above the Fermi level.
  • Wada, Y, Wang, Y, Matsuda, O, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 198 (Pt 2) 732 - 735 0022-3093 1996 [Refereed][Not invited]
     
    Photoluminescence spectra of Ge(SxSe1-x), glasses are investigated with respect to their composition and excitation-energy dependence. Even if the S content, x, is increased to 0.99, the photoluminescence spectra mainly involve those of g-GeSe2 glasses as their ingredient. This result indicates that the luminescence mainly occurs in Se-related luminescent centers. The excitation-energy dependence of the photoluminescence intensity of Se-rich and S-rich samples shows a similar tendency to those of GeSe2 and GeS2 glasses, respectively. We conclude that the energy transfer from S sites excited by light to Se sites is responsible for the observed phenomena.
  • Nakamura, M, Wang, Y, Matsuda, O, Inoue, K, Murase, K
    Journal of Non-Crystalline Solids 198 (Pt 2) 740 - 743 0022-3093 1996 [Refereed][Not invited]
     
    The photo-induced crystallization phenomena in amorphous GeSe2 film are studied by time resolved Raman spectroscopy with varying the spot size of the excitation laser light. The enlargement of the spot size increases the growth probability of the low temperature crystalline phase, while the high temperature crystalline phase dominates under the small spot. A model for understanding these results is proposed in terms of the temperature profile under the irradiation area. The fact that the threshold excitation power density at the onset of crystallization is independent of the spot size suggests that the electronic excitation by light plays an important role in the photo-induced crystallization process.
  • Inoue, K, Matsuda, O, Murase, K
    Physica B-Condensed Matter 219-20 520 - 522 0921-4526 1996 [Refereed][Not invited]
     
    The characteristic peaks, A at 211 and A* at 216 cm(-1), in the Raman spectra of layered crystalline GeSe2 have been studied by a model calculation using a valence force field and bond polarizability (VFF-BP). The A phonon is extended along the GeSe4 tetrahedral chain, while the A* phonon is quasi-localized at the edge-sharing GeSe4 tetrahedra. An extended VFF-BP model including interlayer interactions between Se atoms is proposed to understand the peculiar weakness of the A* Raman intensity.
  • INOUE, K, HUANG, HK, TAKEUCHI, M, KIMURA, K, NAKASHIMA, H, IWANE, M, MATSUDA, O, MURASE, K
    Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 34 (2B) 1342 - 1344 1347-4065 1995 [Refereed][Not invited]
     
    Quantum wires are fabricated by the growth of the AlGaAs system on vicinal (110) GaAs substrates misoriented toward (111)A. It is concluded that during the growth of AlGaAs, composition modulation occurs on the large-step structure almost independently of the temperature, while the large-step structure is formed by the growthonly below a transition temperature. The photoluminescence (PL) from a single quantum wire is observed witha much narrower spectral width as compared with the PL from multi-quantum wires. © 1995 The Japan Society of Applied Physics.
  • MATSUDA, O, OE, H, INOUE, K, MURASE, K
    Journal of Non-Crystalline Solids 193 524 - 528 0022-3093 1995 [Refereed][Not invited]
     
    The photo-induced crystallization process in amorphous GeSe2. is investigated by time-resolved Raman spectroscopy with continuous or periodic light (4880 Angstrom) from an Ar ion laser. It is shown that the electronic and thermal processes work cooperatively to achieve the photo-crystallization. It is found that the periodic excitation experiments reveal the dynamical aspects of the process during latent periods before the crystallization. In particular, a relatively long dark period (10 ms) in the periodic excitation reverses the evolution process in the amorphous state.
  • HOSOKAWA, S, HARI, Y, ONO, I, NISHIHARA, K, TANIGUCHI, M, MATSUDA, O, MURASE, K
    Journal of Physics-Condensed Matter 6 (15) L207 - L214 0953-8984 1994 [Refereed][Not invited]
     
    The conduction-band density of states of amorphous (a-) GeSe2 photo-dissolved by Ag and Cu metals has been examined by means of inverse-photo-emission spectroscopy (IPES). The characteristic feature of the IPES spectrum of a-GeSe2 rapidly smears out with the photo-dissolution of Ag or Cu metal, and each spectrum of the fully photo-doped samples is quite similar to that of a-GeSe1.5. This result is consistent with a structural model in which the dopant atoms are surrounded by four Se atoms and many Ge-Ge bonds are induced by photo-dissolution. We also measured the change of the IPES spectra in the process of Ag photo-doping.
  • アモルファス半導体の光誘起原子移動 --- フォトドーピングと光誘 起結晶化 ---
    井上 恒一, 松田理, 邑瀬 和生
    固体物理別冊特集号「電子励起による非平衡ダイナミックス--- 新物質科学の創出に向け て ---」 71 - 78 1993 [Refereed][Not invited]
  • Hisao Nakashima, Kenta Kimura, Masamichi Sato, Koichi Inoue, Kenzo Maehashi, Shigehiko Hasegawa, Masaaki Iwane, Osamu Matsuda, Kazuo Murase
    Shinku 36 (11) 862 - 868 0559-8516 1993 [Refereed][Not invited]
     
    Quantum wire-like structures are formed in the AlGaAs/GaAs superlattices grown on vicinal GaAs (110) surfaces by MBE. SEM and EPMA observations reveal that the formation of giant steps and orientation dependent AlAs mole fraction of AlGaAs layers induce the quantum wire-like structures. Using RHEED, it is found that the step structures of AlGaAs surfaces depend on growth temperatures (diatomic steps above 600°C, giant steps below 600°C), while all the GaAs and AlAs surfaces consist of regular arrays of diatomic steps. Using this phenomenon, quantum wire structures are naturally formed by growing AlAs/AlGaAs/AlAs quantum wells on vicinal GaAs (110) surfaces with giant growth steps. The photoluminescence strongly polarized parallel to the wire direction gives a clear evidence for the formation of quantum wire structures. © 1993, The Vacuum Society of Japan. All rights reserved.
  • INOUE, K, KIMURA, K, MAEHASHI, K, HASEGAWA, S, NAKASHIMA, H, IWANE, M, MATSUDA, O, MURASE, K
    Journal of Crystal Growth 127 (1-4) 1041 - 1044 0022-0248 1993 [Refereed][Not invited]
     
    Quantum wire structures are formed by the molecular beam epitaxial growth of AlAs-AlGaAs-AlAs quantum well on the large-growth-step structures of superlattices on vicinal (110) GaAs substrates. From the PL spectra, Al compositions in the wire are estimated to be much smaller than those in the well layers. The PL is polarized parallel to the wire direction. The observed large polarization supports the carrier confinement to the quantum wire structures.
  • HOSOKAWA, S, NISHIHARA, K, HARI, Y, TANIGUCHI, M, MATSUDA, O, MURASE, K
    Physical Review B 47 (23) 15509 - 15514 0163-1829 1993 [Refereed][Not invited]
     
    The unoccupied electronic structure of amorphous GeSe2 has been investigated by means of inverse-photoemission spectroscopy. We have found prominent peaks at 2.1 and 4.7 eV above the Fermi level, and another weak and broad peak at about 8 eV. The energy positions of these peaks are consistent with those of the calculated density of states of conduction bands and those expected from the imaginary part of dielectric function obtained by the optical reflectance measurement. By comparison with the Ge 2p,3d, and Se 3d core-absorption spectra, the first and second peaks are assigned to the antibonding states of the Ge-Se covalent bonds, and the third peak corresponds to the 4d and/or 5s states of both the Ge and Se atoms. © 1993 The American Physical Society.
  • Kazuo Murase, Osamu Matsuda, Koichi Inoue
    固体物理 アグネ技術センタ- 27 (11) 841 - 850 0454-4544 1992 [Refereed][Not invited]
  • INOUE, K, MAEHASHI, K, NAKASHIMA, H, MATSUDA, O, MURASE, K
    Superlattices and Microstructures 12 (1) 77 - 80 0749-6036 1992 [Refereed][Not invited]
  • INOUE, K, MATSUDA, O, MAEHASHI, K, NAKASHIMA, H, MURASE, K
    Japanese Journal of Applied Physics Part 2-Letters 31 (8A) L997 - L1000 0021-4922 1992 [Refereed][Not invited]
     
    Depth profiles of Raman scattering and the photoluminescence (PL) properties of anodized porous Si have been studied by micro-measurement techniques. In Raman spectra a remarkable low-energy shift and broadening of the optical phonon line are observed as compared with the bulk Si phonon line basically owing to the phonon confinement. In the depth profiles the PL shows blueshift correlating with the low-energy shift of the Raman peak as the measured point approaches the surface. The redshift of the PL peak has been observed with the low-energy excitation in normal-incidence experiments. It is concluded that the structural depth inhomogeneity strongly affects the optical properties of porous Si.
  • MATSUDA, O, INOUE, K, NAKANE, T, MURASE, K
    Journal of Non-Crystalline Solids 150 (1-3) 202 - 206 0022-3093 1992 [Refereed][Not invited]
     
    The Raman scattering spectra of various forms of GeSe2, such as amorphous films, single crystals, and small crystals prepared by a gas-evaporation deposition technique, are investigated with an excitation photon energy ranging from 2.1 to 2.8 eV. In the spectra of the crystals, there are two Raman bands, originating from two types of breathing vibrations of the GeSe4/2 tetrahedra: one is spread over the corner-sharing tetrahedra and the other is quasi-localized on the edge-sharing tetrahedra. In addition to the resonant Raman scattering related to the edge-sharing tetrahedra through the exciton transition observed with 2.71 eV excitation in the single crystals, a new resonant spectrum is found only in the small crystals with 2.54 eV excitation. With increasing disorder in the crystals, the intensity ratio between the two breathing vibration bands increases in the off-resonant excitation region. The Raman spectra in the amorphous states are ascribed to the breathing vibrations of GeSe4/2 tetrahedra which form a medium-range structure topologically similar to that of crystalline fragments.
  • INOUE, K, MATSUDA, O, MURASE, K
    Journal of Non-Crystalline Solids 150 (1-3) 197 - 201 0022-3093 1992 [Refereed][Not invited]
     
    The characteristic Al peak at 199 cm-1 and the A1C peak at 216 cm-1 in the Raman spectrum of amorphous GeSe2 were compared with the peaks at 211 and 216 cm-1 in the spectrum of crystalline GeSe2. It was proved that the crystalline 216 cm-1 peak is an intrinsic mode which is enhanced by the bulk exciton transition. From a model calculation using a valence force field and bond polarizability, the 211 cm-1 peak was assigned to in-phase breathing vibrations extended along the GeSe4 tetrahedral chain structure, while the 216 cm-1 peak was attributed to in-phase breathing vibrations quasi-localized at the GeSe4 edge-sharing tetrahedra. The phonon density of states in the crystal has a doublet peak similar to the amorphous Raman spectrum. A correspondence between the amorphous and the crystalline Raman spectra was proposed.
  • INOUE, K, MATSUDA, O, MURASE, K
    Solid State Communications 79 (11) 905 - 910 0038-1098 1991 [Refereed][Not invited]
     
    Raman spectra of GeX2 (X = S and Se) crystals in high (HT) and low (LT) temperature forms have been studied on the view point of the connectivity of GeX4 tetrahedra. The characteristic Raman bands are understood by a simple valence-force-field model combined with a bond polarizability model. The most intense Raman bands in HT-GeX2 have been assigned to tetrahedral A1 vibrations extended in the chain structures along the [100] direction. Quasi-localized A1 vibrations in the bridge structures in HT-GeX2 are responsible for a higher side-band of the main band. The main bands in the spectra of LT-GeX2 have been assigned to nearly degenerated A1 vibrations linearly extended in the two chains along the [001] direction. The difference between the spectra of GeS2 and GeSe2 has been roughly explained to be due to the difference between atomic masses.
  • MATSUDA, O, INOUE, K, MURASE, K
    Solid State Communications 75 (4) 303 - 308 0038-1098 1990 [Refereed][Not invited]
  • O MATSUDA, K INOUE, K MURASE
    20TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, VOLS 1-3 2135 - 2138 1990 [Refereed][Not invited]
  • SHON, LH, INOUE, K, MATSUDA, O, MURASE, K, YOKOGAWA, T, OGURA, M
    Solid State Communications 67 (8) 779 - 782 0038-1098 1988 [Refereed][Not invited]

Books etc

  • Ultrasonics --- Physics and applications
    Osamu Matsuda, Oliver B. Wrigh (ContributorChapter 4 Picosecond laser ultrasonics)
    IOP publishing 2022/10 (ISBN: 9780750349345)
  • 音響キーワードブック
    松田 理 (Contributorレーザー超音波)
    コロナ社 2016 424-425
  • Phononic Crystals: Fundamentals and Applications
    Osamu Matsuda, Oliver B. Wright, eds. Abdelkrim Khelif, Ali Adibi (ContributorChap. 7, Optical characterization of phononic crystals in time domain)
    Springer 2015 191-213
  • Osamu Matsuda, Oliver B. Wright, eds. Ken-ichi Shudo, Ikufumi Katayama, Shin-ya Ohno (ContributorChap. 7, Generation and Observation of GHz--THz Acoustic Waves in Thin Films and Microstructures Using Optical Methods)
    Springer 2014 (ISBN: 9783642405938) 129-151
  • Current Topics in Amorphous Materials --Science and Technology--
    Kazuo Murase, Koichi Inoue, Osamu Matsuda (Joint workMedium-range structure and relaxation in chalcogenide glasses investigated by Raman scattering)
    Elsevier, Amsterdam 1993

Conference Activities & Talks

  • 2次元フォノニック結晶の GHz 音響特性の任意周波数イメージング法を用いた解 析  [Invited]
    松田理, 村本裕貴, 古賀裕章, 西田浩紀, 藤田健太郎, 友田基信, ライトオリバー
    第80回応用物理学会秋季学術講演会  2019/09
  • Two-dimensional Imaging of Zero-Group-Velocity Lamb Waves  [Invited]
    Oliver B. Wright, Qingnan Xie, Sylvain Mezil, Paul H. Otsuka, Motonobu Tomoda, Jerome Laurent, Zhonghua Chen, Osamu Matsuda
    第80回応用物理学会秋季学術講演会  2019/09
  • Time-resolved imaging of GHz acoustic waves/vibrations in phononic crystals and metamaterials  [Invited]
    Osamu Matsuda
    METANANO 2019  2019/07
  • Time-resolved imaging of gigahertz surface acoustic waves: recent development and applications  [Invited]
    Osamu Matsuda
    Laser Ultrasonics 2018  2018/07
  • ime-resolved two-dimensional imaging of gigahertz acoustic waves in phononic crystals and related structures  [Invited]
    Osamu Matsuda
    Photonics West 2018  2018/02
  • Time-domain Brillouin scattering assisted by diffraction gratings  [Invited]
    O. Matsuda, T. Pezeril, I. Chaban, K. Fujita, V. E. Gusev
    2017 International Congress on Ultrasonics  2017/12
  • Ultrafast imaging of acoustic wave propagation in microsphere-based metamaterial structures  [Invited]
    P. H. Otsuka, S. Mezil, V. Gusev, O. Matsuda, M. Tomoda, T. Gan, N. Boechler, A. A. Maznev, N. Fang, O. B. Wright
    The 8th International Conference on Metamaterials, Photonic Crystals, and Plasmonics (META '17)  2017/07
  • Optical detection of picosecond acoustic waves generated in grating structures  [Invited]
    Osamu Matsuda, Thomas, Pezeril, Ievgeniia Chaban, Vitalyi Gusev
    19th International Conference on Photoacoustic and Photothermal Phenomena (ICPPP19)  2017/07
  • Time-resolved Imaging of Surface Acoustic Waves Propagating in Two-dimensional Phononic Crystals  [Invited]
    Osamu Matsuda, Hiroki Nishita, Hiroaki Koga, Paul H. Otsuka, Motonobu Tomoda, Oliver B. Wright
    the 4th international conference on phononic crystals/metamaterials, phonon transport/coupling and topological phononics  2017/06
  • Mapping surface phonons in phononic crystals in real- and k-space  [Invited]
    Paul Otsuka, Ryota Chinbe, Motonobu Tomoda, Osamu Matsuda, Oliver B. Wright, Istvan Veres, Joo-Hyung Lee, Jun-Bo Yoon
    Phononics 2013  2013/06
  • Time-resolved imaging of the negative refraction of GHz surface acoustic waves in phononic crystals  [Invited]
    O. Matsuda, Hiroaki Koga, Motonobu Tomoda, Ryota Chinbe, Hirotaka Sakuma, Paul, H. Otsuka, Istvan A. Veres, Oliver B. Wright
    Phononics 2013  2013/06
  • Picosecond laser ultrasonics in GaAs/AlGaAs quantum wells containing spin-polarized excited carriers  [Invited]
    O. Matsuda, C. Li, R. Harley, O. B. Wright, P. Lagoudakis
    International Congress on Ultrasonics -- ICU 2013  2013/05
  • Time-resolved two-dimensional imaging of GHz surface acoustic waves in phononic crystals and structures based on them  [Invited]
    O. Matsuda
    International School of Quantum Electronics, Second Mediterranean International Workshop on Photoacoustic & Photothermal Phenomena: Focus on Biomedical and Nanoscale Imaging and NDE  2012/04
  • Picosecond laser ultrasonics in materials physics  [Invited]
    O. Matsuda
    International School of Quantum Electronics, Second Mediterranean International Workshop on Photoacoustic & Photothermal Phenomena: Focus on Biomedical and Nanoscale Imaging and NDE  2012/04
  • Dynamic imaging of surface acoustic waves in phononic crystals  [Invited]
    Oliver B. Wright, Istvan A. Veres, Dieter M. Profunser, Osamu Matsuda, Brian Culshaw, Udo Lang
    SPIE Smart Nano+Micro Materials and Devices  2011/12
  • Imaging gigahertz vibrations trapped in phononic crystal cavities  [Invited]
    Oliver Wright, Ryota Chinbe, Paul H. Otsuka, Motonobu Tomoda, Osamu Matsuda, Yukihiro Tanaka
    16th International Conference on Photoacoustic and Photothermal Phenomena  2011/11
  • Dynamic imaging of gigahertz phonons on phononic crystal slabs  [Invited]
    O. B. Wright, R. Chinbe, P. H. Otsuka, M. Tomoda, O. Matsuda, Y. Tanaka, I. A. Veres, S. Kim, H. Jeon
    Phononics 2011  2011/05
  • Time-resolved two-dimensional imaging of GHz surface acoustic waves in 1D and 2D phononic crystals and devices based on them  [Invited]
    Osamu Matsuda, Istvan A. Veres, Oliver B. Wright
    Photonics West 2011  2011/01
  • Measurement of surface displacement in picosecond laser acoustics free from the photoelastic effec  [Invited]
    O. Matsuda, K. Aoki, T. Tachizaki, O. B. Wright
    International Congress on Ultrasonics -- ICU 2009  2009/01
  • Surface acoustic waves propagating on microstructured phononic crystals  [Invited]
    D. Profunser, O. Wright, O. Matsuda, Y. Tanaka, A. Khelif, V. Laude, S. Benchabane
    Acoustics '08  2008/06
  • Measurement of the velocity dispersion and attenuation in a liquid metal at GHz frequencies  [Invited]
    O. Wright, B. Perrin, O. Matsuda, V. Gusev
    Acoustics '08  2008/06
  • Stroboscopic interferometric full-field imaging of laser-induced surface acoustic waves  [Invited]
    B. Sarens, O. Matsuda, X. Xu, G. Kalogiannakis, R. Salenbien, R. Cote, C. Glorieux
    Acoustics '08  2008/06
  • Optical detection of longitudinal and shear acoustic waves with laser picosecond acoustics  [Invited]
    O. Matsuda, O. B. Wright, D. H. Hurley, V. Gusev, K. Shimizu
    Acoustics '08  2008/06
  • Visualizing high-frequency surface acoustic waves propagating in microstructured phononic metamaterials  [Invited]
    Dieter M. Profunser, Oliver B. Wright, Osamu Matsuda, Udo Lang, Abdelkrim Khelif, Sarah Benchabane, Vincent Laude
    International Congress on Ultrasonics  2007/04
  • Inversion techniques applied to picosecond acoustics  [Invited]
    M. Tomoda, R. Li Voti, O. Matsuda, O. B. Wright
    Thermo International 2006  2006/07
  • Internal friction and dispersion at GHz frequencies in liquid mercury  [Invited]
    O. B. Wright, B. Perrin, O. Matsuda, V. E. Gusev
    The 14th International Conference on Internal Friction and Mechanical Spectroscopy  2005/09
  • Picosecond acoustic phonon pulses generated and detected with ultrashort optical pulses  [Invited]
    Osamu Matsuda
    Japanese Physical Society Meeting  2005/09
  • Generation and detection of picosecond shear acoustic pulses with ultrashort laser pulses in anisotropic materials  [Invited]
    Osamu Matsuda, Oliver Wright, David Hurley, V. E. Gusev, K. Shimizu
    World Congress on Ultrasonics - Ultrasonics International 2005  2005/08
  • Picosecond acoustics in semiconductor quantum wells  [Invited]
    O. Matsuda, T. Tachizaki, T. Fukui, J. J. Baumberg, O. B. Wright
    Photonics West 2005  2005/01
  • Measurement of dispersion relations of point-excited surface acoustic waves  [Invited]
    O. B. Wright, O. Matsuda, Y. Sugawara
    Ultrasonics International 2003  2003/06
  • Picosecond acoustics in quantum wells  [Invited]
    O. Matsuda
    Gordon Research Conference on Photoacoustic & Photothermal Phenomena 2003  2003/06
  • Real time imaging of surface acoustic waves in thin films and microstructures  [Invited]
    O. B. Wright, Y. Sugawara, O. Matsuda, V. E. Gusev
    12th International conference on Photoacoustic and Photothermal Phenomena  2002/06
  • Real time imaging of surface acoustic waves on opaque substrates  [Invited]
    O. B. Wright, Y. Sugawara, O. Matsuda
    Autumn Meeting of the Acoustical Society of Japan  2002
  • Ripples on crystals  [Invited]
    O. B. Wright, Y. Sugawara, O. Matsuda
    2nd Phonon Engineering Forum  2002
  • Real time imaging and dispersion of surface phonons  [Invited]
    Oliver B. Wright, Yoshihiro Sugawara, Vitalyi E. Gusev, Osamu Matsuda
    Phonons 2001  2001/08
  • Spatiotemporal mapping of surface acoustic waves in isotropic and anisotropic materials  [Invited]
    Yoshihiro Sugawara, Oliver B. Wright, Osamu Matsuda, Vitalyi E. Gusev
    Ultrasonics International 2001  2001/07
  • Study of new transduction mechanisms for laser picosecond acoustics  [Invited]
    David H. Hurley, Oliver B. Wright, Osamu Matsuda, Vitalyi E. Gusev, Oleg. V. Kolosov, K. Sueoka, K. Mukasa, A. Subagyo
    Ultrasonics International / World Congress on Ultrasound  1999/06

MISC

Industrial Property Rights

Awards & Honors

  • 1994/10 日本真空協会 第19回熊谷記念真空科学論文賞
     GaAs(110)微傾斜面上のAlGaAs分子線成長と量子細線構造の形成 
    受賞者: 中島 尚男;木村 憲泰;佐藤 正道;岩根 正晃;井上 恒一;前橋 兼三;長谷川 繁彦;松田 理;邑瀬 和生

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/07 -2026/03 
    Author : 鶴田 健二, 竹澤 晃弘, 松田 理, 畑中 大樹, O・B Wright
     
    本研究では，計算科学的バンド設計に基づいてトポロジーで保護されたエッジモードの発現を予測，力学系にモデル化・可視化，その知見からエッジモードを介した極めて低損失な音波・弾性波伝搬実現を目指している。初年度は各班で以下の取組・成果が得られた。 【(岡大+早大)班】 これまでに設計したC3v対称性を持つ水中2次元フォノニック構造を薄膜系に拡張し，kHz～MHz帯でエッジモードが発現するフォノニック構造を設計した。並行して，既知構造をベースに，位相最適化法を用いてより高いロバスト性を持つ最適構造探索に成功，また，それらのプロトタイプ構造を３Dプリンタで試作し，レーザードップラー計測を行った。一方，GHz帯の設計構造は北大班ならびにNTT班で試作・評価を実施中である。 【北大班】 すでに着手しているフォノニック構造中を伝搬する表面弾性波の時間分解計測による可視化については，強誘電体基板上の銅ピラー構造によるフォノニック結晶で分散関係取得のための予備的な測定を行った。マクロスコピックなメカニカルフォノニック結晶におけるトポロジカルエッジモードの可視化については，回転可能なメカニカルグラフェン構造を設計・製作し，モーションキャプチャーシステムによる同構造の振動測定と解析を進めている。 【NTT班】(岡大+早大)班がGHz帯で設計したトポロジカルフォノニック導波路構造をMEMS作製技術の援用により試作し，エッジモード励起も確認した。並行して，磁性体装荷のGHzフォノニック結晶素子を作製し，強磁性マグノンによる共振周波数とQ値の変化を確認した。同時に，有限要素法を用いた数値解析法を構築し，計算による当該素子構造における磁気弾性変調効果のシミュレーションを行った。 また，代表者・分担者・協力研究者による「トポロジカルフォノニクス研究会」を年度内に４回オンライン開催し多数の参加者を得ている。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 松田 理, 友田 基信
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2022/04 -2025/03 
    Author : 友田 基信, 松田 理
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2019/06 -2022/03 
    Author : Wright Oliver
     
    We propose the development and quantitative interpretation of acoustic and phoxonic metamaterial devices from kHz to GHz frequencies, opening new frontiers in metamaterials. We will generate acoustic waves with frequencies ~0.1 kHz-1 GHz and wavelengths from the millimeter scale down to micro- and nano-scales to control bulk, rod, plate and flexural acoustic waves in both fluid and solid metamaterials, as well as developing the new field of phoxonic, i.e. simultaneous photonic and phononic, metamaterials with the aim to create practical devices. We will investigate metamaterial-based acoustic microscopy, metasurfaces for air-water transmission, lightweight single-component metapillars, metaplates or meta-atoms for wideband multimode acoustic isolation or sub-diffraction limit focusing, as well as the creation of phoxonic metamaterials.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Matsuda Osamu
     
    In this project, we have established the experimental method to achieve the time-resolved two-dimensional imaging of GHz surface acoustic waves at arbitrary frequencies. The technique overcomes the restriction of the existing techniques, i.e. the insufficient frequency resolution. The technique can be utilized to the development of materials and devices which exploit surface acoustic waves. We have used the developed technique to study the properties of the phononic band gaps of phononic metamaterials, of the zero group velocity modes of Lamb waves on a plate, etc. We also have established the way to control the chirality of the acoustic field. As a related study, we have designed and fabricated a metamaterial rod structure which shows the perfect band gap, i.e. the band gap for all the possible acoustic modes at certain frequency range.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2019/03 
    Author : Wright Oliver, Otsuka Paul H., Mezil Sylvain, Devaux Theabaut, Gusev Vitalyi E., Voti Roberto Li, Juodkazis Saulius, Maznev Alex A., Dehoux Thomas, Lee Sam H.
     
    This research concerns GHz ultrasonic computed tomography, which extends the field of non-invasive acoustic internal imaging to the nanoscale. We make use of the optical generation of coherent phonons with frequencies up to ~100 GHz and wavelengths down to ~50 nm in nanostructures to image bulk acoustic waves on very small temporal (~1 ps) and spatial (~50-500 nm) scales. Elastic property imaging, nanoscale acoustic-optic interactions and defect phonon scattering are investigated. This work should lead to new sensing and imaging technologies.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2019/03 
    Author : Tomoda Motonobu, Otsuka Paul H., Mezil Sylvain, MINAMIMOTO Hiro, NOMURA Masahiro, Gusev Vitalyi E., Balogun Olwaseyi
     
    We controled GHz elastic waves propagating on plates with nanoscale thickness using artificial phononic structures as follows. We designed double negative flexural wave metamaterials and simulated negative refractions. We designed a plasmonic phononic crsytal with perfect phononic bandgap. We imaged surface acoustic waves on a microsphere-based elastic metamaterial structure. We measured reflectivity change on split ring resonators due to mechanical vibrations.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2018/03 
    Author : Matsuda Osamu, PEZERIL Thomas, FUJITA Kentaro
     
    To achieve the fast time-resolved two-dimensional imaging of GHz surface acoustic waves using two dimensional imaging device, we performed the following studies. 1) The interferometer optics which transfers images of surface displacement caused by the acoustic vibration to the imaging plane of the camera as the intensity images has been prototyped, and its functionality has been confirmed. 2) Self-adopted interferometer setup using photo-refractive crystal has been considered. 3) The software for the fast transfer and analysis of images for high-speed CCD camera has been developed. As the secondary studies, 4) the light scattering theory for the quantitative handling of the modulation of the light reflection by the acoustic waves has been developed, and 5) the optical generation of detection of acoustic waves using nano-scale metal grating structure has been studied.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/10 -2016/03 
    Author : Wright Oliver, MATSUDA Osamu, TOMODA Motonobu, Otsuka Paul, Mezil Sylvain, Gusev Vitali, Lee Sam Hyeon, Kuipers L. Kobus
     
    We investigate gigahertz acoustic metamaterials, extending them to the nanoscale and thus facilitating the development of new nanoscale acoustic microscopies. The aim is to optically generate coherent phonons with frequencies ~1-100 GHz and wavelengths down to ~100 nm in nano-metamaterials to control bulk and surface acoustic waves on very short temporal (~1 ps) and spatial (~20-50 nm) scales. Applications include solid-state super-lensing, extraordinary transmission, negative refraction, surface acoustic wave cloaking, metamaterial resonators and hybrid opto-mechanical materials. We concentrate on three main topics: 1. Design of GHz acoustic metamaterials, 2. GHz extraordinary transmission, metamaterial resonators, and deep-sub-wavelength focusing, 3. Hybrid GHz opto-mechanical metamaterials. During the course of this work a number of supplementary applications were conceived at lower frequencies.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/04 -2016/03 
    Author : Tomoda Motonobu, WRIGHT Oliver B., MATSUDA Osamu, Otsuka Paul, Mezil Sylvain, Juodkazis Saulius, Ulbricht Ronald, Gusev Vitali
     
    We developed ultrasonic microscopy techniques with high frequencies and high resolutions, aiming to measure and image surface topographies and three-dimensional internal structures of samples. This technique is based on laser picosecond ultrasonics which generate and detect ultrasonic pulses at 10-100 GHz. We did ultrasonic focusing with micro-structures like a micro-ultrasonic-lens and a micro-fiber, making a smaller probe light spot by use of a high numerical aperture oil-immersion objective lens, high resolution depth-profile ultrasonic measurements in transparent samples, development of arbitrary frequency measurements which are not restricted to repetition pulse laser frequencies, and controlling of pump beam spot shapes.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2010 -2012 
    Author : OLIVER B. Wright, MATSUDA Osamu, TOMODA Motonobu, OTSUKA Paul, JEREMY Baumberg, L. KOBUS Kuipers
     
    By means of an ultrafast optical technique, we investigate the coupling of high frequency phonons at GHz frequencies with metallic plasmonic structures. Various samples are probed, including nanovoid arrays, lattices of tiny holes exhibiting extraordinary optical transmission (EOT) and nanoscale linear waveguides. For the nanovoid arrays, we reveal GHz breathing vibrations of the voids by 2D imaging, showing how the vibrations couple to localized Mie plasmons. For the EOT samples, we reveal collective vibration of the hole arrays, and their effect on the optical transmission modulation. For the waveguides we describe work in progress, and fabrication of nanoscale linear gold waveguides.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2008 -2011 
    Author : MATSUDA Osamu, WRIGHT Oliver, TOMODA Motonobu
     
    We aimed to transfer the excitons and to control their life time in semiconductor samples using the surface acoustic waves generated by the ultrashort light pulse absorption. For this purpose, we developed an experimental technique which allows the time resolved two-dimensional imaging of the GHz surface acoustic wave propagation and the two-dimensional imaging of the photoluminescence at the same region of the sample at low temperature (10K). Connecting to this, we also developed a heterodyne technique which use the modulated light for both excitation and probing light. We also developed an analyzing method for the strain components using the polarization of the probing light.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2007 -2009 
    Author : O・B Wright
     
    This work involves the imaging and control of phonon modes confined in a wide variety of novel microscopic geometries with unprecedented picosecond temporal, micron spatial, and megahertz frequency resolutions. The following topics are investigated : visualizing Bloch waves and modes in phononic crystals, phononic crystal waveguides and cavities, investigating whispering gallery modes, acoustic negative refraction, and phase singularities in surface acoustic wave fields, and applications to industrially-produced surface acoustic wave resonators. Visualization and Mode-Control of Phonons Confined in Microstructures
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2005 -2007 
    Author : MATSUDA Osamu, WRIGHT B. Oliver, TOMODA Motonobu
     
    Picosecond acoustic pulses can be used to study the internal structure of medium in nanometer spatial region, or the electron and lattice dynamics of medium in picosecond temporal region. Especially a method named picosecond laser ultrasonics, which uses ultra short light pulses for the generation and detection of the acoustic pulses, has been exploited to evaluate the thickness profile and elastic properties of multilayers, or to study the ultrafast dynamics of photo-induced carriers. In the previous studies, mostly the longitudinal acoustic waves have been used because of the symmetry of the system. However, the additional usage of shear acoustic waves would be favorable to extend the applicability of the method. This research aims to develop the picosecond laser ultrasonics using shear acoustic waves and to apply the method to various studies in materials physics. The main achievements are as follows. 1) With the low symmetry surface of the anisotropic medium such as Zn and GaAs single crystals, the laser picosecond ultrasonics measurement is carried out. We develop a general light scattering theory for the inhomogeneously modulated multilayers of anisotropic medium. With this theory, the experimental results were quantitatively analyzed to retrieve the photoelastic tensor components, ultrasonic absorption coefficients, electron-phonon interaction coefficients, etc.. 2) We develop a method for the picosecond laser ultrasonics measurement in liquids. The acoustic pulses are generated at the GaAs single crystal and their propagation in water and glycerol is studied. 3) We develop a method to measure the surface displacement caused by the acoustic waves independent of the photoelastic signal. 4) We develop a theory for the acoustic wave propagation in inhomogeneous medium. 5) We develop a method to map the elastic properties of polycrystalline medium with the anisotropic acoustic wave propagation. The method is utilized to study the Cu polycrystals and the artificial phononic crystals.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2004 -2005 
    Author : WRIGHT O・B, 松田 理, 友田 基信, 田村 信一朗
     
    我々は、ローマ大学「ラ・サピエンザ」のR.Li Voti博士から提供された高精度のTiO_2/Ag多層膜試料を用い、試料中を伝播するピコ秒超音波の広範囲にわたる波長依存性・時間分解の測定を行った。同期した2つの波長可変な超短パルスレーザーシステムを使い、反射率変化の応答を観測した。この試料はフォトニックバンドギャップを波長400nm以下と800nm以上の光に対してもつので、ポンプ光の波長を800nmに固定してプローブ光の波長を400nm付近のバンドギャップエッジの周りで変化させ測定を行った。 プローブ光の波長を400nmから長波長側へ走査し、プローブ光の波長により試料の反射率変化が増大することを発見した。これは、1次元フォトニック構造においてフォトニックバンドギャップが超高速音響光学作用を増大することに利用できることを結論付けるものである。 我々はまた、プローブ光が試料中で多重反射する効果も含めた転送行列法によって、試料中を伝播するピコ秒超音波による反射率変化についての数値的なシミュレーションを行った。この理論結果は、すべてのプローブ光の波長領域において実験結果と一致し、これは初めてフォトニック構造におけるピコ秒時間領域での音響光学変調を定量的に評価したことになる。 この研究は、さらに2次元や3次元フォトニック結晶におけるピコ秒音響光学作用に研究を拡張する基礎となるものである。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2001 -2005 
    Author : WRIGHT Oliver B., MATSUDA Osamu, TOMODA Motonobu
     
    1)THz phonon generation and detection experiments were done on 2-well and 3-well GaAs/GaAlAs samples with surface-absorbed probe optical pulses and wavelength-tuned pump optical pulses. These first spectroscopic experiments in the domain of picosecond acoustics (up to 0.3 THz) were successfully treated with theoretical models to describe the phonon generation and detection in these multilayers. We also characterized the spectral generation efficiency. 2)Improvements in temporal and spatial resolution were achieved using shorter (〜400 fs) optical pulses to demonstrate detection at frequencies up to 0.5 THz. We also developed a new optical-polarization-sensitive oblique-incidence technique, tested on Cr, to separate different signal contributions, and modelled the phonon pulse shapes for this sample. 3)A Novel ultrafast Sagnac interferometer was developed for picosecond phonon detection with 1 μm spatial resolution, applicable to semiconductors, involving a single focusing objective. 4)Bulk GaAs picosecond acoustics was implemented to help interpret the quantum well results, we investigated ultrafast phonon generation in 3 different GaAs samples. We demonstrate the generation of picosecond shear pulses using anisotropic cuts and pulse-broadening by electron diffusion. 5)A novel detection scheme based photoluminescence was extensively tested on quantum well samples. The results show that we require a higher detection sensitivity to achieve detection of phonon -pulses detection within a quantum well rather than at the surface.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2002 -2003 
    Author : MATSUDA Osamu, TOMODA Motonobu, TAMURA Shin-ichiro, WRIGHT B. Oliver
     
    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.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2000 -2001 
    Author : MATSUDA Osamu, INAGAKI Katsuhiko, MUTO Shunichi, WRIGHT B. Oliver
     
    In this research, we aim to develop a new microscope which has both nanometer spatial resolution and picosecond temporal resolution. It can be realized by the combination of the scanning probe microscope and the time-resolved measurement technique with ultrashort laser pulses. The former has the nanometer spatial resolution and the latter the picosecond temporal resolution. The combination of the ultra high speed optical switch with ultra short laser pulses and the scanning tunneling microscope has been already proposed along this way. It is proved, however, that the stray capacity between the sample and the microscope tip substantially reduces the spatial resolution when the tunnel current is switched very fast. As a way getting around the above problem, we propose a scanning probe microscope that detects ultrashort phonon pulses excited by ultrashort laser pulses. The ultrashort light pulses from a mode-locked Ti-sapphire laser are divided into two optical paths. An optical delay line is used to introduce a time difference of ± 1 ns between the pulses in two paths. The pulses passing each line are modulated with different frequencies. A metal thin film sample is irradiated by the modulated light pulses to generate the ultrashort acoustic phonon pulses. The generated periodic surface displacement is detected by the atomic force microscopy. We considered this method theoretically and did actual experiments. In addition, we did related studies of the technique to estimate the local elasticity with nanometer spatial resolution by the ultrasonic force microscope and of the ultra high frequency phonon generation by a semiconductor quantum well structure.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2000 -2001 
    Author : WRIGHT Oliver B., 松田 理
     
    本研究は、固体熱物性の空間的分布をナノスケールで画像化できる光学ヘテロダイン原子間力顕微鏡を開発することを目的とした。試料表面においてレーザー照射により光熱的に励起された超音波振動(周波数100MHz以下)の振幅および位相を、ナノメートルの横空間分解能で2次元画像化する。これにより試料表面および表面下の熱的な性質についてのナノメートル空間分解能測定を可能にする。 以下に示すようにして光ヘテロダイン原子間力顕微鏡を構築した。SiN透明カンチレバーを持つ原子間力顕微鏡のカンチレバー支持部に圧電素子をとりつけ、カンチレバーを周波数ω_1=11MHzにて振動させる。探針による試料表面の観察部位にω_1近傍の周波数ω_2で変調された赤外光を照射し試料表面に周期的な熱振動を励起する。試料表面は試料の局所的熱物性を反映してω_2による膨張収縮を繰り返す。試料探針間相互作用の試料探針間距離に対する非線形性により、カンチレバーの平均変位はω_1-ω_2の振動数で変化する。この変化の振幅と位相を原子間力顕微鏡の光てこ検出部を用いて検出し画像化する。試料としてSi基板上にCr薄膜(膜厚100nm)およびSiO_2/Cr薄膜(膜厚150nm/100nm)を作製したものを用いた。これらは同一基板上にμmスケールのモザイク状に形成されている。試料表面層は同一膜厚のCr層で覆われているので、表面から100nm深さまでの機械的な性質は試料表面の場所によらないようになっている。この試料についての光ヘテロダイン顕微鏡による観測を行った。試料表面下のSiO_2層の有無による熱物性の違いを反映して、位相像に大きなコントラストが得られた。1次元熱拡散モデルに基づいてこのコントラストを半定量的に解析した。これらの結果により光ヘテロダイン顕微鏡が試料表面下の局所的熱物性を画像化する有力な手段であることが示された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1999 -2000 
    Author : MATSUDA Osamu, INAGAKI Katsuhiko, MUTO Shunichi, WRIGHT Oliver,b, YAMAMOTO Noritaka
     
    In this research, we develop the scanning ultrasonic probe microscope with lateral resolution < 1 nm and study the physics involved in it. The contributions of elasticity, viscosity, surface energy at the sample-tip interface to the sample and cantilever dynamics are analyzed distinctively in order to carry out the quantitative measurement on the surface and subsurface local complex elasticity. A commercial AFM is modified by attaching the PZT transducer at the cantilever base or on the scanner to make the scanning ultrasonic probe microscopy which is capable to apply the ultrasonic vibration to the cantilever or the sample. At various frequency below and above the cantilever resonance frequency and at various ultrasonic amplitude, we carry out the force curve measurement on Si and GaAs single crystals. The vibration amplitude is calibrated with Michelson enterferomenter. The obtained force curve has the following common features : 1)In case of no applied vibration, small "jump-in" in the approach phase and large "jump-out" in the retraction phase are observed. 2)Within creasing the vibration amplitude, the "jump-out" position rapidly approaches to the "jump-in" position. 3)At above certain vibration amplitude, a new "repulsive jump' is observed for both approach and retraction phase. These results are analyzed by considering the cantilever motion numerically with the finite difference method. In the analysis, we give the elasticity of the tip and sample, damping, adhesion, and assume the JKR model for the tip-sample interaction. The result explains the features 1)and 2)quantitively and proves the validity of the analysis.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1999 -2000 
    Author : WRIGHT Oliver b., MATSUDA Osamu, TAMURA Shinichiro
     
    In main aim of this study is to extend our knowledge of ultrafast acoustic phonon generation using femtosecond light pulses to basic metallic materials and nanostructures. The phonon pulse propagation dynamics in such materials and the phonon generation mechanisms can be studied. The use here of a tightly focused excitation and probe light beams a few microns in diameter allow the detection of phonons with -10 μm spatial resolution. In order to do this we have made use of an ultrafast reflectometry and interferometry for measurements at normal incidence. We have carried out the first generation and detection of coherent phonons in amorphous and liquid metals. The results for Hg demonstrate that electron diffusion is very likely to be influencing the phonon generation. An interesting asymmetric pulse shape was observed. The first demonstration that picosecond phonon pulses could be generated and detected in an amorphous metal was also successful. Coherent phonon generation and detection experiments in transition metals with -100 fs optical pulses, in particular for Cr and for Ni, shows that we can successfully model the phonon pulse shapes with the two-temperature model, taking due account of ultrasonic attenuation measured in experiment. Ultrashort optical pulse experiments in transition metals with -10 fs optical pulses have been attempted for the first time. Using a -20 fs order optical pulse width in the infrared for both the pump and probe beams, the effect of ultrafast electron diffusion on ultrashort timescales is clearly evident in the data for a series of films of different thicknesses. A striking reversal in polarity of the signals for thicker films was observed. Preliminary results for the generation of coherent phonon pulses in multilayer metal structures show that electron diffusion must be taken into account in order to explain the observed acoustic echoes. Related theoretical work was successful in elucidating the way light is modulated by strain on reflection or transmission through a multilayer structure. This can be done not only for longitudinal coherent phonons but also for shear coherent phonons.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1997 -2000 
    Author : MURASE Kazuo, MATSUDA Osamu, INOUE Koichi, WANG Yong
     
    We have presented a comprehensive study of the roles of nanoscopic structural units in chalcogenide glasses in relaxation behaviors around glass transition temperature, structural changes toward crystallization, electronic structures around band-tails, and relaxation processes of photoexcited carriers. First, we have shown that the variation of Se_n (n>2) chain segments essentially determines relaxational behaviors of networks. We have also shown that the compositional dependence of resonant Raman spectra is explained by the variation in lengths of the Se_n chain and the CST chain. Second, we have found that intrinsic inhomogeneity in Ge-Ge ethan-like units, Se-Se bonds, and fragments similar to β-GeSe_2 can cause significantly different macroscopic structural changes in GeSe_2 glass. Finally, we have demonstrated that threefold-coordinated Se atoms forming Se-Se bonds play a key role in the photoinduced structural change and the dynamics of photoexcited carriers in GeSe_2 glass.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 1998 -1999 
    Author : 松田 理
     
    物質の準安定状態であるガラス状態は、通常、熱的な励起により、安定な結晶状態に移行する。アモルファスカルコゲナイド半導体ではこの転移を光照射によって起こすことができる。光には偏光方向の自由度があるので、このような構造変化にかかわる特徴的な方向(例えば結晶軸)を励起光の偏向方向によって制御できる可能性がある。本研究では、光誘起構造変化現象における光励起状態の緩和過程の果たす役割について調べる。 アモルファスカルコゲナイド半導体における、光励起直後の電子励起状態の緩和過程を調べることを目指して。フェムト秒光パルスを用いたポンププローブ超高速過渡的反射率変化測定装置を組み立てた。この測定装置に用いる新しい共通パス型の干渉計を開発した。本装置により試料のピコ秒時間領域の反射率変化および表面変位を検出することができる。 装置の評価のためにアモルファスSi薄膜についての測定を行った。結果を定量的に理解するために、薄膜試料内での熱伝搬、超音波伝搬、電子格子相互作用を考慮したモデルの構築を行った。また、等方的なアモルファス物質中に光によって誘起される非等方的な誘電率変化を検出するための実験配置について詳しい検討を行った。
  • Ultra high frequency phonon pulse generation and detection in solids and liquids
    Date (from‐to) : 1998
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1995 -1996 
    Author : MATSUDA Osamu, INOUE Koichi
     
    Amorphous chalcogenide semiconductors which contain the elements of group VI show various kinds of photo-induced structural changes such as photo-darkening, photo-bleaching, photo-crystallization, etc.. These changes are caused by lattice deformations which result from the relaxation of the photo-excited electrons through the strong electron-phonon interaction. It is also important that the amorphous states are not in the thermal equilibrium. The chalcogen atoms which are in two-fold coordinated are considered to play an important role, but the details of the mechanism is still not clear. For example, it is still unknown how the excited electron distorts the lattice. To know the relaxation process of the excited electron in the amorphous and crystalline GeSe_2 which is a typical chalcogenide semiconductor, the time resolved photo-luminescence measurement was carried out. Both phases have the band-gap in visible region (2.2-2.7eV). The excitation by band-gap light causes a broad Gaussian-shaped photo-luminescence in near-infra-red region (-1eV). The large Stokes-shift is due to the strong electron-phonon interaction. The continuous wave laser light is modulated by an acousto-optic modulator and then used for the excitation source of the time-resolved measurement. The measured time region was 100ns-3ms after the cut-off of the excitation light. There are many similarities in the spectral shape between the amorphous and crystalline GeSe_2. This result shows that the initial states of the luminescence are similar in both materials. As for the time-profile, the crystalline GeSe_2 shows the single exponential decay, while the amorphous GeSe_2 shows the extended exponential decay. The later is caused by the energy distribution of the luminescent centers by structural fluctuation in the glass.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 1992 -1992 
    Author : 松田 理

Educational Activities

Teaching Experience

  • Advanced Physics and Technology of Materials
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 光の伝播、光と物質の相互作用、固体のバンド構造と光学的性質
  • Inter-Graduate School Classes(General Subject):Natural and Applied Sciences
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 電磁気学、分極、波動方程式、等方性・異方性、光の反射・透過
  • Inter-Graduate School Classes(General Subject):Natural and Applied Sciences
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : optical spectra, metals, semiconductors, dielectrics, direct transition, indirect transition
  • Advanced Physics and Technology of Materials
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 光の伝播、光と物質の相互作用、固体のバンド構造と光学的性質
  • Physics I
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 運動、力、運動の法則、仕事、エネルギー、運動量、保存則、剛体、流体、単振動、音と光、干渉、回折
  • Introduction to Modern Physics
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 量子力学、光の粒子性、物質の波動性、特殊相対性理論、物性物理学

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