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Proceedings Paper

Time-resolved microscopy using variable probe wavelengths for ultra-short pulse interaction (Conference Presentation)
Author(s): Klaus Bergner; Malte Kumkar; Andreas Tünnermann; Stefan Nolte; Brian Seyfarth
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Paper Abstract

Glass processing with ultrashort laser pulses allow for different material modifications, ranging from smooth refractive index changes which can be used for the generation of waveguides up to large disruptions due to accumulates stress for glass separation. These disruptions, generated by a dense electron plasma, are favored for glass dicing applications. To tailor the resulting material response a fundamental understanding of the laser/material interaction is of interest. Therefore, we analyze the spatio-temporal evolution of free carriers induced by ultrashort laser pulses using a pump-probe setup with high temporal and spatial resolution and various probe wavelengths.

Single laser pulses with 1026nm wavelength, 6ps (FWHM) pulse duration and 200μJ pulse energy were applied to fused silica, Borofloat 33 and Gorilla glass. Electron densities around 1 x 1020cm-3 in the focal plane and 1 x 1019cm-3 in front of the focus are obtained, independent from the glass type used.

The free carriers slowly decay within several ns, while the decay time depends on both the maximum electron densities reached and glass species. In this process a part of the excited electrons relax within several 10ps into a long-living stage where a transient effect is observed. Here, various probe wavelengths show differences in the recorded signal.

A further carrier relaxation leads to permanent (stress, voids) and non-stable (color center) modifications crucial for precise glass dicing applications.

Paper Details

Date Published: 21 April 2017
PDF: 1 pages
Proc. SPIE 10094, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVII, 100941C (21 April 2017); doi: 10.1117/12.2255884
Show Author Affiliations
Klaus Bergner, Friedrich-Schiller-Univ. Jena (Germany)
Malte Kumkar, TRUMPF Laser- und Systemtechnik GmbH (Germany)
Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Stefan Nolte, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Brian Seyfarth, Friedrich-Schiller-Univ. Jena (Germany)


Published in SPIE Proceedings Vol. 10094:
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVII
Alexander Heisterkamp; Peter R. Herman; Michel Meunier; Roberto Osellame, Editor(s)

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