Bulk properties of excitons in external electric field studied by coherent band dynamics

Bulk properties of the exciton-polariton dispersion in the presence of a uniform electric field and for frequencies near the first excitonic resonance are studied within the framework of Stahl's coherent band dynamics. A relative simple expression for the excitonic susceptibility (and thus for the dispersion relation) is derived and applied for calculating the field dependence of the transverse excitonic frequency. By an appropriate choice of a certain fitting parameter the calculated energy shift agrees satisfactorily with experimental values obtained recently by Schultheis and Kohler