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UNIVERSITE Pierre & Marie CURIE La science à PARIS Bernard Perrin International Workshop on « Nanoscale Energy Conversion and Information Processing Devices.

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Presentation on theme: "UNIVERSITE Pierre & Marie CURIE La science à PARIS Bernard Perrin International Workshop on « Nanoscale Energy Conversion and Information Processing Devices."— Presentation transcript:

1 UNIVERSITE Pierre & Marie CURIE La science à PARIS Bernard Perrin International Workshop on « Nanoscale Energy Conversion and Information Processing Devices » - September 24-26, 2006, Nice - France - "NANO-ACOUSTICS AND TERAHERTZ ACOUSTICS"

2 Probing vibrations at the nanoscale LA TA Fréquency (THz) 10 1, , piezo Brillouin Picosecond acoustics IXS Wavevector q/  (u.a.) nano- systems neutron Sound wave velocity in solids 5 – 10 nm/ps Phonons : nm scale THz range  What can be done with an optical pump probe technique to increase the frequency range of laser ultrasonics?  Phonon engineering  Phonon nanocavities Ballistic phonon heat transport Picosecond acoustics (H. Maris, 1985)

3 probe pump L substrate > a few hundreds  m L film > a few tens nm substrate reflectometry interferometry Nanometric sonar in thin films

4 Lattice dispersionLattice anharmonocity

5 (MgO) Dispersion and nonlinearity : Solitons 150 fs (1.4nm) Stable solution (soliton) Non linearity Dispersion

6 Multi-soliton formation Rectangular initial strain Area conservation

7 Acoustic Nonlinearity Non linearity - Harmonic distorsion - sound velocity = f(  ) - Acoustic rectification GaAs pump probe Al-30 nm 356  m [100]

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15 Ballistic propagation of heat pulses Z-cut in Sapphire - T = 3.8 K time longitudinal phonons tranverse phonons Black body radiation Spectrum up to a few THz Q

16 GaAs/AlAs

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18 reflectometry Can we do the same with a pump probe technique? T = 15 K GaAs pump probe Al-30 nm 356  m [100] One way + 6 round trips One way + 2 round trips interferometry First longitudinal coherent acoustic echo (one way trip)

19 Temperature dependence Q = 0.12 nJ

20 Position (  m) Delay (ps) 12 K - Q=0.6 nJ pump Al 30 nm Al 30 nm probe at different locations XY scan in the detection surface Heat pulse : moving acoustic source v ph. v st. v st  v ph : building up of a large matter displacement

21 Phonon engineering and acoustic nanocavity

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24 Acoustic mirrorAcoustic nanocavity

25 Nanocavity used as a phonons generator cavity GaAs 356 µm pump probe

26 Selective excitation of the cavity mode

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28 Nanocavity or mirror used as a phonon detector GaAs 356 µm Acoustic mirror pumpprobe

29 Laurent Belliard – INSP Alex Fainstein – Institut Balseiro (Bariloche) Agnès Huynh - INSP Bernard Jusserand - INSP Daniel Kimura- Lanzillotti (INSP/Institut Balseiro - Bariloche) Aristide Lemaitre (LPN – Marcoussis) Emmannuel Péronne - INSP Shuo Zhang - INSP  Phonon engineering in the subterahertz range is possible  Semiconductor superlattices work as excellent acoustic Bragg mirrors  Acoustic nanocavity has been evidenced  A first step towards a SASER

30 12 th international conference on phonon scattering in condensed matter  Phonons in nanostructures and low-dimensional structures  Ultrafast acoustics  Coherent phonons  Micro and nano acoustics  MEMS and NEMS (micro and nano electromechanical systems)  Phonons in devices for electronics, optoelectronics and spintronics  Electron-phonon interaction  Micro and nanoscale phonon heat transfer  Nanoscale energy conversion and thermo-electricity  Phonon transport  Solitons and nonlinear phenomena  Acoustic waves in anisotropic media and phonon imaging  Phonons in superconductors and magnetic materials  Phononic crystals  Surface and Interface phonons  Quantum fluids  Lattice dynamics  Phonons in glasses and disordered systems  Phase transitions  Light, neutron and X-ray inelastic scattering  New techniques  Particle detectors July 15–20, 2007


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