Optical absorption in asymmetric double quantum wells driven by two intense terahertz fields

Abstract

Optical absorption is investigated for asymmetric double quantum wells driven by a resonant terahertz field and a varied terahertz field, both polarized along the growth direction. Rich nonlinear dynamics of the replica peak and the Autler-Townes splitting of various dressed states are systematically studied in undoped asymmetric double quantum wells by taking account of multiple factors, such as the frequency of the varied terahertz field and the strength of the resonant terahertz field. Each electron subband splits into two dressed states when the resonant terahertz field is applied in the absence of the varied terahertz field, the optical absorption spectrum shows the first-order Autler-Townes splitting of the electron subbands. When a varied terahertz field is added into the resonant system, the replica peak and the second-order Autler-Townes splitting of the dressed states near the band edge respectively emerge when the varied terahertz field is non-resonant and resonant with these dressed states. When the strength of the resonant terahertz field is increased, the first-order Autler-Townes double peaks and the replica peak in the optical absorption spectrum shift with the shifts of the dressed states. The presented results have potential applications in electro-optical devices.