Kiel 2004 – scientific programme

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K: Kurzzeitphysik

K 5: Poster Kurzzeitphysik

K 5.6: Poster

Wednesday, March 10, 2004, 17:45–19:45, Foyer

Femtosecond Laser-Induced Breakdown in Fluorides - Comparison of Single-Shot and Multi-Shot Ablation Thresholds — •Sebastian Eckert¹, Florenta Costache^1,2, Phillippe Martin³, Alexandre Semerok⁴, Olivier Gobert³, and Jürgen Reif^1,2 — ¹LS Experimentalphysik II, Brandenburgische Technische Universität Cottbus, Universitätsplatz 3-4, 03044 Cottbus, Germany — ²JointLab IHP/BTU Cottbus, Universitätsplatz 3-4, 03044 Cottbus, Germany — ³CEA Saclay, DSM/DRECAM/SPAM, 91191 Gif sur Yvette Cédex, France — ⁴CEA Saclay, DPE/SPCP/LSLA, 91191 Gif sur Yvette Cédex, France

Single-shot ablation thresholds from single crystalline targets of BaF₂ and CaF₂, irradiated under high vacuum by 50-100-fs laser pulses at 800 nm and 400 nm, respectively, are measured and compared to multi-shot ablation thresholds at significantly lower laser intensity. We investigate and compare crater diameter, depth and ablated volume using an optical profilometer and atomic force microscope inspection.

Previous studies [1], indicate that the actual damage occurs through the relaxation from a highly non-equilibrium state. While at lower intensity, in the multi-shot regime, the basic mechanism was shown to be pure Coulomb explosion of an electrostatically charged surface, at increasing laser intensity, a threshold can be assigned for the onset of a phase explosion. The single and multi-shot threshold measurements indicate the impact on the surface breakdown of the two different regimes.

[1] J. Reif, F. Costache, M. Henyk, S.V. Pandelov: Appl. Surf. Sci. 197-198, 891 - 895 (2002).