Optical observation of interactions between extended and localized states in a GaAs/AlGaAs waveguide superlattice structure

Abstract

The authors present theoretical and experimental investigation of absorption in a GaAs quantum well (QW) embedded in an AlGaAs short-period superlattice (SL) An exact numerical calculation for a QW-SL system reveals a field-induced interaction between the light-hole and electron states localized in the QW and SL extended states, which results in a specific resonance (step-like) reduction of the electron and light hole overlap. Room-temperature light-hole excitonic electroabsorption measured in a graded refractive index waveguide with a QW embedded in the SL is shown to be in qualitative agreement with theoretical predictions. The structure provides an extremely low-voltage modulation with a waveguide absorption change of 430 cm-1 at 1.5 V.