Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 108: Poster: Ultra-fast phenomena / Optical properties / Semiconductor laser / Devices and device concepts
HL 108.3: Poster
Donnerstag, 3. April 2014, 17:00–20:00, P1
Towards Nonlinear Phononics, probing acoustic phonon wave packets with X-ray and visible light — •Andre Bojahr1, Matthias Gohlke2, Marc Herzog3, Daniel Schick1, Peter Gaal4, and Matias Bargheer1,4 — 1Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam/Golm, Germany — 2Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany — 3Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 4Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, Albert-Einstein-Str. 15, 12489 Berlin, Germany
We use ultrashort visible and hard X-ray pulses as a real-time probe of the occupation of phonon modes constituting large amplitude phonon wave packets. These time-domain Brillouin scattering experiments permit the time-resolved observation of the phonon dynamics including phonon damping and nonlinear interaction. High strain fields lead to nonlinear phenomena like sum and difference-frequency mixing, which depend strictly on the shape of the excited phonon wave packet. Via multiple pumping of an epitaxially grown metal transducer film on a SrTiO3 substrate we generate spectrally narrow phonon wave packets. The nonlinear evolution such a wave packet can be understood by difference and sum-frequency mixing of its spectral components, explaining the amplitude dependent damping of phonon wave packets. Our measurements are supported by calculations of a nonlinear masses and springs model, which describes the experiments quantitatively.