Public Physic Colloquium in the Summer Terms 2012 in Münster
Place:     Germany, 48149 Münster, Wilhelm-Klemm-Str. 10, IG I, HS 2
Time:     Thursday, 10.05.2012  16:00 h c.t.
Colloquium Coffee at 15:45 h  at the Lecture Hall

Femtosecond Laser Volume Structuring of Transparent Materials: Potential and Applications
Prof. Dr. Stefan Nolte, Friedrich-Schiller-Universität Jena, Institut für Angewandte Physik

Within the past decade, the use of ultrashort laser pulses has found widespread attention for precise microstructuring. Particularly, the possibility to realize localized modifications within the bulk of transparent materials has recently attracted increasing interest. When intense ultrashort pulses are tightly focused into the transparent bulk material, the intensity in the focal volume can be come high enough to initiate absorption through nonlinear field ionization. This results in the creation of an electron-ion plasma, leading to permanent structural changes inside the sample without affecting the surface. Depending on the processing parameters, either refractive index changes (isotropic or birefringent) or microvoids can be generated in the focus.
In this presentation, the basic principles of the femtosecond laser internal structuring approach as well as various applications will be discussed. Especially, localized refractive index changes can find applications in different fields including the direct writing of embedded waveguides and waveguide arrays, fiber Bragg gratings (FBG) or volume Bragg gratings (VBG). Working at high repetition rates, even cumulative effects can become important, and the ultrashort laser pulses might be used as a localized heat source within the volume, e.g. for the direct bonding without adhesives and minimized thermal stress.

Invited from: Prof. Dr. C. Fallnich

By Order of the Professors of the Department of Physics

Prof. Dr. Sergej Demokritov