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Coherent acoustic phonons in phonon cavities investigated by asynchronous optical sampling

Kohärente akustische Phononen in Phononenaktivitäten untersucht mittels asynchronem optischen Abtasten
: Hudert, F.; Bartels, A.; Janke, C.; Dekorsy, T.; Köhler, K.


Phonons 2007, 12th International Conference on Phonon Scattering in Condensed Matter : 15-20 July 2007, Paris, France
Bristol: IOP Publishing, 2007 (Journal of physics. Conference series 92.2007)
Art. 012012, 4 pp.
International Conference on Phonon Scattering in Condensed Matter (Phonons) <12, 2007, Paris>
Conference Paper, Journal Article
Fraunhofer IAF ()
III-V semiconductor; III-V Halbleiter; superlattice; Übergitter; time resolved spectroscopy; zeitaufgelöste Spektroskopie

Using a recently introduced measurement technique, called asynchronous optical sampling (ASOPS), we have investigated the dynamics of coherent acoustic phonons in a semiconductor heterostructure composed of a GaAs film between two GaAs/AlAs superlattices, serving as a cavity for acoustic phonons. Measurements were performed at liquid helium temperatures. The possibility to perform two-color pump-probe spectroscopy allowed us to tune the probe pulse energy to the cavity band gap, while sweeping the pump pulse energy over the superlattice resonance. The large measurement window of 1 ns in combination with a resolution of about 150 fs made a detailed analysis of the observed phonon dynamics possible. We observed a long lived oscillation in the gap of the phonon dispersion at 466 GHz, which we attribute to a cavity mode.