We study the coherent dynamics of interband and intraband polarizations of Bloch oscillations in a GaAs/Al0.7Ga0.3As 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.
© 1996 Optical Society of America
P. Leisching, T. Dekorsy, H. J. Bakker, H. G. Roskos, H. Kurz, and K. Köhler, "Dephasing and selection rules of interband and intraband polarizations in superlattices," J. Opt. Soc. Am. B 13, 1009-1015 (1996)