Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 43: Poster II

Q 43.41: Poster

Mittwoch, 20. März 2013, 16:00–18:30, Empore Lichthof

Recombination effects in dielectrics irradiated with ultrashort intense laser pulses — •Nils Brouwer and Bärbel Rethfeld — TU Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663 Kaiserslautern, Deutschland

Ultrashort laser pulses of high intensity are of increasing importance in material processing and fundamental research. In order to control or avoid laser damage to transparent dielectrics, a proper understanding of the involved microscopic processes is necessary. When modeling laser-excited dielectrics to trace dielectric breakdown, the valence band is often assumed to be fully occupied during the laser excitation. While this assumption certainly holds if the free electron density is several orders of magnitude below the valence band electron density, at high laser intensities its validity has to be examined, since recombination effects as Auger recombination can have a significant influence on the energy and particle density even on the subpicosecond timescale, if a considerable fraction of valence band states is unoccupied.

We extended our previous Boltzmann approach [1,2] with an equation to model valence band dynamics and included collision integrals for Auger recombination. We present results for the free electron density, the free electron energy density and the phonon energy density with and without valence band dynamics.
 [1]  A. Kaiser, B. Rethfeld, M. Vicanek, G. Simon,
   Phys. Rev. B 61, 11437 (2000)
 [2]  B. Rethfeld, H. Krutsch , D.H.H. Hoffmann,
   Contrib. Plasma Phys. 50, 16 (2010)