Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 11: Photonic Dielectrics II

DF 11.3: Talk

Wednesday, March 25, 2009, 15:30–15:50, WIL A317

Femtosecond white-light pump-probe investigation of laser-induced shape transformation of silver nanoparticles in glass — •Armin Warth, Gerhard Seifert, Jens Lange, and Heinrich Graener — Fachbereich Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle

Soda lime-glasses containing spheroidal silver nanoparticles are used as the base material for production of high-quality polarisers, dichroic optical microstructures or long-time optical data storage. Permanent shape transformation of the nanoparticles can be induced by irradiation with intense femtosecond laser pulses. The most efficient transformation to spheroids with large aspect ratio is achieved in ’multi-shot mode’, where several hundred laser pulses in the range of 0.2 - 0.5 TW/cm² on average hit one spot on the sample.

To study the ultra short dynamics of such irreversible, shot-by-shot increasing changes, we introduce a highly efficient femtosecond pump - supercontinuum probe setup, which allows us to monitor the changes of optical density with single shot precision. Thus we obtain the complete temporal evolution of spectral changes for each of the several hundred laser shots separately. I.e., after only one measurement cycle we end up with a data set that needs typically 3GB space for data storage. Examples for the results of these experiments are presented and discussed.