Modeling energy transfer and transport in laser-excited dielectrics

Oliver Brenk; Nils Brouwer; Anika Rämer; Orkhan Osmani; Bärbel Rethfeld

doi:10.1117/12.978845

4 December 2012 Modeling energy transfer and transport in laser-excited dielectrics

Oliver Brenk, Nils Brouwer, Anika Rämer, Orkhan Osmani, Bärbel Rethfeld

Proceedings Volume 8530, Laser-Induced Damage in Optical Materials: 2012; 85300G (2012) https://doi.org/10.1117/12.978845
Event: SPIE Laser Damage, 2012, Boulder, Colorado, United States

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.

Citation Download Citation

Oliver Brenk, Nils Brouwer, Anika Rämer, Orkhan Osmani, and Bärbel Rethfeld "Modeling energy transfer and transport in laser-excited dielectrics", Proc. SPIE 8530, Laser-Induced Damage in Optical Materials: 2012, 85300G (4 December 2012); https://doi.org/10.1117/12.978845

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