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Dephasing and selection rules of interband and intraband polarisations in superlattices

Phasenentmischung und Auswahlregeln von Interband- und Intrabandpolarisationen in Übergittern


Journal of the Optical Society of America. B, Optical physics 13 (1996), S.1009-1015
ISSN: 0740-3224
ISSN: 1520-8540
Fraunhofer IAF ()
heterostructure; Heterostruktur; III-V Halbleiter; III-V semiconductors; quantum-well; time resolved optical measurement; zeitaufgelöste Messung

We study the coherent dynamics of interband and intraband polarizations of Bloch oscillations in a GaAs/ Al(0.7)Ga(0,3)As semiconductor superlattice. Time-resolved measurements of both polarizations are simultaneously performed by combination of four-wave mixing and an electro-optic detection scheme in one experimental setup. This combination allows us to gain a much more comprehensive picture of the dynamics of a multi-level system. Distinctive differences in the oscillation frequencies and the dephasing of both polarizations are found. They arise from the fact that excitonic quantum beats are observed in four-wave mixing, whereas a quantum interference of electrons in continuum states is detected in the electro-optic signal. As a consequence, the polarizations are governed by different selection rules that explain the pronounced differences in the oscillation frequencies found for specific experimental conditions.