Polarization dependence of degenerate four-wave mixing on 2D excitons in GaAs quantum wells

The polarization dependence of the coherent optical response of GaAs QWS reveals that modelling of 2D excitons as non-interacting two-level systems is inadequate. Extensions of the model taking into account many-body Coulomb effects and disorder-induced coupling of the valence band states results in a fairly good description of all experimental data.