The role of Coulombic coupling in electroabsorption of square quantum wells

The impact of Coulombic coupling between different subband pairs, on the qu antum confined Stark effect in square quantum wells, has been studied. It i s shown, via detailed comparison between electroabsorption spectra obtained from a full excitonic Green function calculation, a decoupled excitonic Gr een function calculation and measurement, that inclusion of the Coulombic c oupling between different subband pairs is generally required for correct p rediction of electroabsorption in square wells, especially for shallow or n arrow square quantum wells. These results are of particular significance fo r the accurate calculation of electrorefraction, by Kramers-Kronig transfor mation, of quantum well electroabsorption spectra.