||J. Feldmann, K. Leo, J. Shah,
D. A. B. Miller, J. E. Cunningham, T. Meier, G. vonPlessen, A. Schulze, P.
Thomas, S. Schmitt-Rink "Optical investigation of Bloch oscillations in a
semiconductor superlattice" Physical Review B, 46, 7252-7255 (1992).
authors report the study of optical dephasing of Wannier-Stark ladder excitations in a
semiconductor superlattice by means of transient degenerate four-wave mixing. They observe
pronounced modulations of the signal with a time period varying linearly with the electric
field. The time period is found to equal the temporal periodicity of Bloch oscillations,
in agreement with theory. In addition, they find that the dephasing time decreases with
increasing localization of the Wannier-Stark states, which is attributed to carrier escape
out of the lowest miniband
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