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K: Fachverband Kurzzeitphysik

K 6: Laserstrahlwechselwirkung, Lasermaterialbearbeitung I

K 6.2: Vortrag

Donnerstag, 15. März 2012, 11:45–12:00, V57.04

Modeling laser-induced dielectric breakdown: Application of the multiple rate equation — •Oliver Brenk and Bärbel Rethfeld — Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany

Material processing with ultrashort laser pulses is in the focus of experimental and theoretical research. Here the dielectric breakdown, a strong increase in the absorptivity of a former transparent dielectric, is of special interest. Due to the absorbed laser energy material modification can happen. A key player in the energy transfer from laser to lattice is the electronic system. Applying the multiple rate equation (MRE), introduced in [1], we investigate the temporal evolution of the electronic density in the conduction band. The MRE is a tool to numerically simulate the effects of ultrashort laser pulse irradiation on the electronic system of a dielectric. The inclusion of optical parameters, like surface reflectivity and refractive index, depending on the electronic density in the conduction band, enables us to investigate dielectric breakdown. Calculating the free electron density evolution during irradiation, we can trace absorption and breakdown. We follow the latter independent of the assumption of a certain critical electron density. The current implementation of the MRE includes a spatial dimension, thus we can estimate up to which depth breakdown occurs.

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