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Proceedings Paper

Reflectivity oscillations from fs-laser excited Bismuth: excitation of coherent phonons
Author(s): Davide Boschetto; Eugene G. Gamaly; Andrei V. Rode; David Glijer; Thomas Garl; Olivier Albert; Antoine Rousse; Jean Etchepare
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Paper Abstract

We present the experimental and theoretical studies of the optical response from the single-crystal of bismuth to the excitation by the femtosecond laser pulse. The experimental results revealed a complex, first - positive and a few picoseconds later - negative, change in time-dependent reflectivity, which could not be explained in the light of the existing theories. It is shown that reflectivity oscillations are related to the excitation of coherent phonons by the pulse with duration shorter of all relaxation times. We demonstrate that swiftly heated electrons are responsible for the phonon excitation due to the fast modification of the attractive (electronic) part of inter-atomic potential. The electronic perturbation of potential is also responsible for the red shift of phonon frequency and for the increase in the amplitude of phonons. The coherent phonon excitation process as well as the change in the reflectivity is related mainly to the modification of the electron-phonon momentum exchange frequency. The comparison between the theory and experiments shows an excellent agreement. Moreover, the reflectivity measurements allow direct recovery of the electron-phonon coupling rate in bismuth crystal, which has not been measured before.

Paper Details

Date Published: 7 June 2006
PDF: 10 pages
Proc. SPIE 6261, High-Power Laser Ablation VI, 62610N (7 June 2006); doi: 10.1117/12.669618
Show Author Affiliations
Davide Boschetto, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)
Eugene G. Gamaly, The Australian National Univ. (Australia)
Andrei V. Rode, The Australian National Univ. (Australia)
David Glijer, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)
Thomas Garl, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)
Olivier Albert, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)
Antoine Rousse, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)
Jean Etchepare, Lab. d'Optique Appliquée, ENSTA/Ecole Polytechnique (France)

Published in SPIE Proceedings Vol. 6261:
High-Power Laser Ablation VI
Claude R. Phipps, Editor(s)

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