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Proceedings Paper

Modeling energy transfer and transport in laser-excited dielectrics
Author(s): Oliver Brenk; Nils Brouwer; Anika Rämer; Orkhan Osmani; Bärbel Rethfeld
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Paper Abstract

To understand laser interaction with dielectrics on a wide time scale we apply different approaches: For a subpicosecond time range we solve complete Boltzmann collision integrals or apply the multiple rate equation (MRE), which focuses on the evolution of the conduction band electron density. The Boltzmann approach includes the valence band dynamics and calculates the transient distribution function for electrons and phonons. It also allows to extract important parameters, like the Auger recombination and impact ionization rate and the electron-phonon coupling parameter, which can be used as input in other models. The multiple rate equation includes density dependent optical parameters and is therefore independent of a critical density criterion to follow dielectric breakdown. The flexibility of the MRE is used to examine, which set of laser parameters causes breakdown, and to convert this knowledge into breakdown maps. It also allows to include a spatial dimension which traces the density evolution in different material depths. This spatial information and the parameters obtained by the Boltzmann approach can be used as input in the density dependent two temperature model (nTTM). The nTTM models heat relaxation and carrier transport on a very wide time scale by using an expanded two temperature model which also includes the transient free electron density. The combination of the individual strengths of our models is capable to simulate a vast range of materials and laser pulses on a timescale of up to several hundred picoseconds and to investigate the effect of transport on the damage threshold.

Paper Details

Date Published: 4 December 2012
PDF: 12 pages
Proc. SPIE 8530, Laser-Induced Damage in Optical Materials: 2012, 85300G (4 December 2012); doi: 10.1117/12.978845
Show Author Affiliations
Oliver Brenk, Technische Univ. Kaiserslautern (Germany)
Nils Brouwer, Technische Univ. Kaiserslautern (Germany)
Anika Rämer, Technische Univ. Kaiserslautern (Germany)
Orkhan Osmani, Donostia International Physics Ctr. (Spain)
Bärbel Rethfeld, Technische Univ. Kaiserslautern (Germany)

Published in SPIE Proceedings Vol. 8530:
Laser-Induced Damage in Optical Materials: 2012
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; M J Soileau, Editor(s)

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