Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 22: Ultrakurze Laserpulse: Anwendungen 1

Q 22.9: Talk

Tuesday, March 15, 2011, 12:30–12:45, SCH A01

Application of the multiple rate equation — •Oliver Brenk, Nils Brouwer, and Bärbel Rethfeld — TU Kaiserslautern, 67663 Kaiserslautern, Germany

Material processing with ultrashort laser pulses is in the focus of experimental and theoretical research. The multiple rate equation, introduced in [1], is a tool to numerically simulate the effects of ultrashort laserpulse irradiation on dielectrics. The MRE allows to investigate the temporal evolution of the electronic density in the conduction band with very good agreement to a full kinetic approach [2] using Boltzman’s equation, but with considerably less computational effort. We expanded the MRE model to include reflectivity at the surface and the recombination into Self-Trapped Excitons (STE-States). The reflectivity, depending on the electronic density, influences the laser intensity inside the material. STEs are localized electron-hole pairs formed by free electrons having recombined with localized holes, energetically lying between valence band and conduction band. Re-excitation out of these states is considered as well. We added a spatial dimension to the already implemented time evolution, in order to study the spatially resolved evolution of the electronic densities. Counting the absorbed laser photons allows us to estimate the absorbed energy per spatial layer.

[1] B. Rethfeld. Phys. Rev. Lett., 92:187401, 2004.

[2] A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon. Phys. Rev. B,61(17):11437*11450,2000.