Dresden 2006 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.45: Poster

Dienstag, 28. März 2006, 15:00–17:30, P2

Self-organised pattern formation upon femtosecond laser ablation — •Olga Varlamova^1,2, Florenta Costache^1,2, Markus Ratzke^1,2, and Jürgen Reif^1,2 — ¹LS Experimentalphysik II, BTU Cottbus, Karl-Wachsmann-Allee 1, 03046 Cottbus — ²IHP/BTU JointLab, Karl-Wachsmann-Allee 1, 03046 Cottbus

Upon multi-shot femtosecond laser ablation from different materials, self-organised regular patterns are observed at the crater bottom. By irradiation with linearly polarised light, it has been shown that long periodic ripples with many bifurcations develop, the orientation of which is determined by the polarisation direction, though the fundamental nature of this correlation is not yet known. To investigate this phenomenon closer, we performed corresponding experiments using circularly and elliptically polarised light. Surface morphology investigation reveals that, again, a variety of self-organised patterns is obtained, from arrays of nanoparticles to bifurcating longer lines. Experiments with laser beams of elliptical polarisation have shown that ripples’ orientation is sensitive to the major axe of the polarization ellipse. However, for circularly polarized light the orientation of these structures is random. Furthermore, electrical measurements done with a Scanning-Probe Microscope on the ablated area reveal the existence of a spatial variation in the electric field response correlated with the patterns’ modulation on the crater bottom.