Hannover 2010 – wissenschaftliches Programm

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K: Fachverband Kurzzeitphysik

K 6: Poster

K 6.10: Poster

Donnerstag, 11. März 2010, 16:30–19:00, Lichthof

Spectral interference to investigate the dynamics of the free electron plasma excited via tailored fs-pulses — •Cristian Sarpe-Tudoran, Matthias Wollenhaupt, Alexander Horn, Jens Köhler, Lars Englert, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

In the process of laser ablation of high band gap materials the first step is the laser induced optical breakdown in which a high density free electron plasma is created. We have shown that by using tailored ultrashort laser pulses the optical breakdown can be manipulated in order to increase the precision of the ablation process about one order below diffraction limit [1]. A better knowledge of the temporal evolution of the plasma density [2] can provide information on the ionization mechanisms involved in the breakdown process; based on this, fs-pulses can be shaped in order to improve the ablation process further. Here we report our studies to investigate the dynamics of the plasma created by fs-laser pulses in a thin water jet by using a robust spectral interference technique. Information about the density of the free electrons produced by tailored pump pulses can be accurately obtained by analyzing the phase shift between a reference and a probe pulse produced in a common-path interferometer. The early times dynamics is obtained with a high temporal resolution as well as its dependence on the laser intensity and temporal pulse shapes.

[1] L. Englert et al. Opt. Express 15, 17855 (2007), Appl. Phys. A 92, 749 (2008) [2] C. Sarpe-Tudoran et. al. APL 88, 2161109 (2006)