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Institut de Physique et Chimie des Matériaux de Strasbourg

Institute for Physics and Chemistry of Materials in Strasbourg. Institut de Physique et Chimie des Matériaux de Strasbourg. Femtosecond spectroscopy in Solids florilège. Charles Hirlimann Directeur de recherche émérite CNRS.

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Institut de Physique et Chimie des Matériaux de Strasbourg

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  1. Institute for Physics and Chemistry of Materials in Strasbourg Institut de Physique et Chimie des Matériaux de Strasbourg

  2. Femtosecond spectroscopy in Solids florilège Charles Hirlimann Directeur de recherche émérite CNRS IPCMS, 23 rue du Lœss B.P. 43, 67034 Strasbourg cedex2, France Mail: Charles.Hirlimann@ipcms.unistra.fr

  3. • Short history of fs pulses generation • Solid state physics spectroscopy • Non-linear optics • Basic Physics

  4. First CPM ever

  5. • Short history of fs pulses generation • Solid state physics spectroscopy • Non-linear optics • Basic Physics

  6. Silicon fusion Thermal fusion Lindemann’s criterion: Atoms displaced by 10% Of the bonds Photo fusion 10% Of the bonds cut By the light flash Fast effect expected

  7. Dynamics of silicon melting Surface 2nd harmonic Spiral Probe filter Pump (100fs) reflection UV beam (111) Silicon wafer

  8. Silicon has a fcc structure Silicon Unit Cell • ternary symmetry along (111)

  9. crystal 2nd harmonic emission (111) Silicon wafer glass Expected emission distributions Experimental result

  10. 2nd harmonic emission (111) Silicon wafer Irradiated @ 620 nm Silicon melts in 300 fs!

  11. Differential transmission n:GaAs low temperature Out of equilibrium Boltzmann distribution With pump unperturbed t = 0 t = 200 fs Differential spectroscopy

  12. Electrons thermalization n:GaAs MQW low temperature Irradiated @ 620 nm Differential spectroscopy gives a direct observation of the electrons bucket; This bucket spreads down to a Boltzmann distribution in a time delay of 200 fs!

  13. • Short history of fs pulses generation • Solid state physics spectroscopy • Non-linear optics in GaSe • Basic Physics in opals

  14. Resonnant optical Stark effect GaSe room temperature 14 meV GaSe 0 meV -9 meV Resonant excitation

  15. Resonant optical Stark effect GaSe room temperature GaS Max shift 10 meV Maximum exciton shift @ -70 fs Pump duration 150 fs Maximum pump 1µJ The maximum exciton shift goes as the square root of the intensity

  16. • Short history of fs pulses generation • Solid state physics spectroscopy • Non-linear optics in CdS • Basic Physics in opals

  17. Pump-probe sketch

  18. Can the two photon absorption saturate? Yes if the deposition of electrons is faster than their thermalization time Yes if the sample does not break down

  19. Defocusing experiment The index of refraction depends on the electron density sample probe Pump This gives access to the thermalization time

  20. Dynamical defocusing measurement Thermalization time 350 fs

  21. Saturation of the two photon absorption

  22. • Short history of fs pulses generation • Solid state physics spectroscopy • Non-linear optics • Basic Physics

  23. Artificial opals Meta crystal of silica beads Poly-disperse opal Mono-disperse opal fcc compact piling of 200 nm silica beads An opal reflects light as a 3D grating

  24. ω =c.k Stop-band An opal reflects light as a 3D grating This creates a stop-band with no propagation and slowing down of light

  25. Tuneable continuum generation Meta crystal of silica beads Short 100 fs tuneable pulses are selected and recompressed from the continuum generated through a short optical fibber

  26. Time-of-flight measure A cross-correlation is measured in the doubling crystal

  27. Group velocity slowing down A time-of-flight measurement directly shows the slowing down of the group velocity induced by the stop-band in the meta-crystal

  28. Carlos Henrique de Brito Cruz Daniel S. Chemla André Chevy Richard L. Fork Pierre Gilliot Bernd Hönerlage Makoto A. Kanehisa Gérard Klein Wayne H. Knox Jean-FrédéricLami Marie May David A. Miller Jean-François Morhange Stéphane Petit jean-Luc Rehspringer Jagdeep Shah Charles V. Shank Benjamin Thomas Yurii A. Vlasov Richard Yen Acknowledgement Merci de votre attention

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