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Subpicosecond four-wave mixing in GaAs/Al(x)Ga(1-x)As quantum wells

Subpikosekunden-Vier-Wellen-Mischen in GaAs/Al(x)Ga(1-x)As Quantum Wells


Physical Review. B 44 (1991), No.11, pp.5726-5737 : Abb.,Lit.
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
Journal Article
Fraunhofer IAF ()
heterostructure; Heterostruktur; III-V Halbleiter; III-V semiconductors; time resolved photoluminescence; zeitaufgelöste Photolumineszenz

We investigate the properties of coherent exciton states in GaAs/AlxGa1-xAs quantum wells using the four-wave-mixing technique with subpicosecond time resolution. In the first part of this work, we show that many-body interactions in a solid manifest themselves in a line shape of the four-wave-mixing signal that is substantially different from the predictions of the generally used simple two-level model. In particular, the coherent interaction of the quasiparticles leads to a signal at negative delay times, in agreement with recent theoretical predictions. In the second part, we report in detail about experiments where energetically close exciton transitions are excited coherently with a short laser pulse. The quantum or polarization interference leads to the observation of quantum beats in the decay of the diffracted signal. These results demonstrate that quantum-beat spectroscopy can be applied to study intrinsic excitations in solids.