Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells

A new quantum interference phenomenon in optical absorption is reported. This effect manifests itself in a striking suppression of the absorption coefficient as a function of the electric field concomitant with a negligible Stark shift of the transition in suitably designed coupled-quantum-well semiconductors. This phenomenon, which does not arise from a reduced overlap of the final and initial states of the transition, is shown to be caused by quantum interference between two spatially separated transitions. The basic and general nature of this mechanism could be exploited in other artificially structured materials as well.