Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 24: Ultra fast phenomena
HL 24.8: Vortrag
Dienstag, 28. März 2006, 17:00–17:15, POT 151
Generation of high-frequency transverse polarized monochromatic acoustic phonons by ultrafast optical excitation in gallium arsenide — •D. Lehmann1, A.J. Kent2, R.N. Kini2, N.M. Stanton2, Cz. Jasiukiewicz3, and M. Henini2 — 1Institute of Theoretical Physics, TU Dresden, D-01062 Dresden, Germany — 2School of Physics and Astronomy, University of Nottingham, NG7 2RD, Nottingham, UK — 3Department of Physics, University of Technology, ul. W. Pola 2, PL-35-359 Rzeszow, Poland
There is interest in developing useable sources of THz monochromatic acoustic phonon beams for applications in phonon spectroscopy, acoustic microscopy, probing of nanostructures etc. In recent years, the generation of high intensity pulses of acoustic phonons by ultrafast optical techniques has been demonstrated, but the work has concentrated mainly on longitudinally polarized phonons [1].
We have generated coherent transverse polarized acoustic phonons by ultrafast optical excitation of GaAs/AlGaAs superlattices grown on low-index planes of GaAs [2]. The frequency of the generated phonons is determined by the superlattice period. The phonons can leak out of the superlattice and propagate over macroscopic distances as a monochromatic pulse. We show that theoretical estimations and pump probe measurements suggest a Raman scattering process is responsible for the coherent phonon generation.
[1] N.M. Stanton, R.N. Kini, A.J. Kent, M.Henini and D. Lehmann, Phys. Rev. B 68, 113302 (2003)
[2] R.N. Kini et al., submitted to Appl. Phys. Lett.