München 2004 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 20: Poster Ultrakurze Lichtimpulse

Q 20.15: Poster

Dienstag, 23. März 2004, 14:00–16:00, Schellingstr. 3

Femtosecond time-resolved investigation of the optical breakdown in water — •Cristian Sarpe-Tudoran, Andreas Assion, Mathias Wollenhaupt, Marc Winter, and Thomas Baumert — University of Kassel, Institute of Physics, Heinrich-Plett-Str. 40, D-34134

Femtosecond laser induced breakdown in dielectric materials was intensively studied in the last decade, due to the applications of this technique in medicine and in high-quality micro- and nano- material processing of transparent media. Even if it is generally accepted that the primary process in the femtosecond laser ablation of transparent dielectrics is the generation of high density free electrons by multiphoton absorption, the mechanism of the energy transfer and the plasma dynamic below 20 ps is not yet understood. In this work we investigate with high temporal and spatial resolution the dynamics of the free electrons plasma produced by ultrashort femtosecond pulses on the surface of dielectric liquids. The plasma dynamics was resolved from the femtosecond up to the nanosecond regime. Transient reflection spectroscopy provided us useful information about the dynamics of the free electrons density, whereas by time resolved imaging techniques we directly investigated the spatial formation and evolution of the induced plasma. Taking into account the spectral and spatial data we are able to reconstruct a three dimensional image of the plasma dynamics with femtosecond resolution.