Dynamics of Bloch oscillations: Influence of excitation conditions

The dynamics of the Bloch oscillations in GaAs/Al0.3Ga0.7As superlattices a re studied experimentally applying spectrally-resolved four-wave mixing in a self-diffraction geometry. We have found that the interband dephasing rat e and the decay rate of the Bloch oscillations have different dependencies on excitation density. We have explored the dynamical features of the Bloch oscillations depending on the number of Wannier-Stark states excited. The conditions for observation of the Bloch oscillations and their harmonics ar e determined, the destructive role of excitons in the decay of the Bloch os cillations is demonstrated.