PROBE. Grundlagen der praezisen, optischen Behandlung von Festkoerpern. Teilvorhaben: Grundlagenuntersuchungen zur Materialstrukturierung und -modifizierung mit ultrakurzen Laserimpulsen Endbericht

Abstract

Main goal of our study ws a better understanding on laser-induced micro-machining of brittle substances that are difficult to process mechanically, such as the technically very interesting transparent dielectric materials (e.g. SiO_2, CaF_2, Al_2O_3, etc.). Quality, topography and morphology of the processed area and ablation rate were analysed in respect to the different optical parameters (pulse width, energy, number of shots, wavelength, etc.) that were varied in our study. One important part of our investigation was the determination of the (surface) damage threshold at different pulse widths and short numbers. We obtained first time results of the shape of bulk modifications through self-focusing of ultra-short laser pulses at different pulse widths, pulse energies and number of shots. We demonstrated the feasibility to utilise this technique for a controlled three dimensional micro-structuring in the bulk, without altering the surfaces. On the basis of Molecular Dynamis (MD) simulation we were able to present theoretical results on the ablation process on an atomic scale in sub-ps time resolution for the first time. As target material we have chosen crystalline silicon for the theoretical modelling of the ablation with ultra-short pulses. To investigate the dynamics of the ablation we successfully introduced a pump-probe-technique monitoring the changes of the scattered light.The experimental results were compared with the theoretical model using the MD simulation. (orig.)SIGLEAvailable from TIB Hannover: F98B1780+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman