Bloch oscillation under a bichromatic laser: Dynamical delocalization and localization, persistent terahertz emission, and harmonics generation

A novel AC driving configuration is proposed for biased semiconductor super lattices, in which the THz driving is provided by an intense bichromatic cw laser in the visible light range. The frequency difference between two com ponents of the laser is resonant with the Bloch oscillation. Thus, multi-ph oton processes mediated by the conduction (valence) band states lead to dyn amical delocalization and localization of the valence (conduction) electron s, and to the formation and collapse of quasi-minibands. Thus, driven Bloch oscillators are predicted to generate persistent THz emission and harmonic s of the dipole field, which are tolerant of the exciton and the relaxation effects.