Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 26: Anwendung ultrakurzer Lichtimpulse II

Q 26.5: Talk

Tuesday, March 20, 2007, 15:00–15:15, 5K

Femtosecond pump-supercontinuum probe investigation on 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 very useful as base material for production of high-quality polarizers, dichroic optical microstructures or long-time optical data storage. In such materials, a permanent shape transformation of the nanoparticles can be induced by irradiation with femtosecond laser pulses above a certain intensity threshold. Our pump-probe setup allows us to investigate the ultrafast dynamics of the deformation process by monitoring the changes of the sample's optical density with spectrally broad femtosecond probe pulses covering the spectral range from ~ 350nm to 550nm, with a typical time resolution of 100fs. While the surface plasmon dynamics of metal particles in glass has been studied at low intensities (no permanent changes) by many groups, only few is known so far about the dynamics of the processes leading to shape transformation above the intensity threshold for permanent changes.

In this contribution, we present novel results on the dynamics of permanent modification of nanoparticles in glass. These very challenging experiments require high experimental accuracy because, due to the permanent optical changes induced by each pump pulse, only a single laser shot can be used at one spot of the sample to probe the transient optical changes at a well-defined delay time.