Observation of excitonic effects on electroabsorption in coupled quantum wells

An experimental study was made on the electroabsorption of asymmetric GaAs double quantum wells separated by thin AlAs tunnel barriers to better understand the optical properties in the coupled systems. It was clearly shown that the field-dependent absorption characteristics, i.e., the anticrossing properties, were not fully explained by the predictions for the optical transitions between the quantized electronic levels but better interpreted by taking account of the contribution of the exciton binding energies, i.e, in terms of tunneling between the excitonic states in the adjacent wells.