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SUMMARY:Gigahertz Ultrasonics in Metamaterials
DTSTART:20180918T100000
DTSTAMP:20260506T205338Z
UID:9af0c6a296b55ecaedfa6c68b038185550afc4e0fd7ab4d5b671fa2a
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Olivier B. Wright\, Hokkaido University\, Japan\nThe Ins
 titute of Microengineering (IMT) and the Lausanne Centre for Ultrafast Sci
 ence (LACUS) are pleased to invite you to the following seminar\, hosted b
 y Prof. Yves Bellouard & Prof. Majed Chergui:\n\nExperiments and simula
 tions on both optical and acoustic metamaterials interacting with GHz vibr
 ations are presented. We firstly consider the extraordinary transmission o
 f GHz surface acoustic waves through nanoscale metamaterial structures bas
 ed on thin resonant bridges\, showing how significant improvements in the 
 acoustic transmission can be obtained at specific resonant frequencies. We
  then present the GHz modulation of the optical extraordinary transmission
  through a nanoscale hole-array structure\, and the GHz modulation of the 
 optical reflection from a split-ring resonator metamaterial that vibrates 
 like an array of tiny tuning forks. Possible applications of this work are
  in ultrafast modulation and sensing. \n\nControlling sound or light is e
 ssential to a diverse range of applications. Periodic and aperiodic acoust
 ic structures formed of individual acoustic or electromagnetic resonators\
 , under conditions in which the acoustic or optical wavelength is much sma
 ller than the resonator spacing\, provide a versatile way to block\, absor
 b\, guide or transmit sound or light. Understanding their behaviour has be
 en the focus of much research. Such structures\, known as metamaterials\, 
 can be constructed from meter to nanometer length scales. We show how\, fo
 r micron-scale to nanoscale structures\, they can be probed using ultrafas
 t optics to generate gigahertz sound fields inside them and be used to mod
 ulate optical transmission\, or achieve enhanced acoustic transmission. Pr
 ospects for applications of GHz acoustic waves in acoustic or optical meta
 materials will also be presented.\n\nBio:\nO. B. Wright initially speciali
 zed in low temperature solid state physics. During his PhD course he publi
 shed a detailed account of the thermoelastic effect in glasses at low temp
 eratures—a modern version of a rubber band experiment in which the tempe
 rature change of the band is monitored on stretching.\n\nAfter obtaining a
 n industrial post he concentrated on applications of optics in sensor phys
 ics\, in particular specializing in the use of ultrashort optical pulses f
 or generating and detecting picosecond acoustic phonon pulses in thin film
 s and multilayers. He developed a related phonon pulse detection technique
  based on the measurement of picosecond surface motion. With this techniqu
 e he demonstrated how ultrafast electron diffusion could be probed in meta
 ls\, and he contributed to the development of a theory of this diffusion\,
  establishing an analytical relationship between the electron energy relax
 ation time and the electron-phonon and electron-electron coupling strength
 s.\n\nFocusing in 2001-2002 at Hokkaido University on semiconductors\, he 
 measured the shape of picosecond acoustic phonon pulses generated in galli
 um arsenide\, and was involved in similar spectroscopic experiments on sem
 iconductor quantum wells.\n\nIn 2002 he also helped establish a method for
  watching ripples on crystals using ultrafast interferometry as well as ma
 king contributions to the theory of the detection of phonon pulses in mult
 ilayers.\n\nHe has also worked on the development of ultrasonic force micr
 oscopy and new local probe imaging techniques based on thermal waves at hi
 gh frequencies and on nanometre length scales.\n\nFrom 2004 he was involve
 d in extending picosecond ultrasonics to shear waves\, to liquids\, and to
  contact mechanics\, as well as spending time watching ripples travelling 
 on phononic crystals and resonators.\n\nMore recently he has worked on gig
 ahertz vibrations of nanostructures\, including plasmonic crystals\, and b
 egun work on acoustic metamaterials.
LOCATION:CM 0 11 http://plan.epfl.ch/?room=?CM011
STATUS:CONFIRMED
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