  A novel DC and AC driving configuration is proposed for semiconductor
superlattices, in which the THz AC driving is provided by an intense
bichromatic cw laser. The two components of the laser, usually in the visible
light range, are near but not exactly resonant with interband Wannier-Stark
transitions, and their frequency difference equals the Wannier-Stark ladder
spacing. Multi-photon processes with the intermediate states in the conduction
(valence) band cause dynamical delocalization and localization of valence
(conduction) electrons, and the corresponding formation and collapse of the
quasi-minibands.
