Aachen PK 2003 – scientific programme

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K: Kurzzeitphysik

K 4: Laser applications

K 4.2: Talk

Thursday, March 20, 2003, 15:30–15:45, F04

Adaptive Femtosecond Laser Material Processing on a Micrometer Scale — •Andreas Assion, Matthias Wollenhaupt, Lars Haag, Christian Horn, Fedor Maiorov, Andreas Präkelt, Cristian Sarpe-Tudoran, Marc Winter, and Thomas Baumert — Universität Kassel, Fachbereich Physik, Heinrich-Plett-Str. 40, D-34132 Kassel

The objective of this work is to optimize the ablation efficiency to improve quality, speed and precession of fs-laser material processing. During the last years fs-laser material processing has proven to be an efficient tool for micro structuring for transparent materials. In many cases, the ablation process can be described by a two step model, where in the first step an electron plasma is created via multi photon and avalanche ionization. In the second step the plasma electron energy is transferred to the lattice on a timescale much longer than the duration of the fs-laser pulse. Due to the multi photon ionization the optimization of the electron plasma generation and therefore the ablation efficiency becomes possible. We present a concept employing a computer controlled fs-pulse shaper in combination with a self learning genetic algorithm to identify the optimal fs-laser pulse shape for plasma generation and ablation. Two optical techniques, transient reflection spectroscopy and laser induced breakdown spectroscopy, are used for measuring the plasma generation and ablation efficiency in a single shot. The concept and first experimental results are presented and discussed.