Polarisation effects for the excitonic stark shift at all detunings

Odile Betbeder-Matibet, Monique Combescot

Monique, R. Combescot

M. Joffre, Daniele Hulin, A. Migus +1 more

Monique Combescot, R. Combescot

The optical Stark shift of the exciton is due to a coupling between the exciton and "semivirtual" biexcitonic states (bound and unbound). We show that at large detuning the excitonic shift is the same as the "dressed atom" blue shift. We predict that at small detuning the exciton-exciton interaction plays an important role and leads to an excitonic red shift at the two-photon absorption threshold when the molecular biexciton is stable.

Monique Combescot, R. Combescot

When a direct-gap semiconductor is irradiated in the transparency region, the exciton line blue shifts. This so-called optical Stark effect of the exciton is due to a coupling between the exciton and all biexcitonic states (bound or unbound). More precisely we show that the exciton shift results only from interactions between excitons (Coulomb interaction and Pauli exclusion). At large detuning, Pauli exclusion dominates, and the excitonic shift is the same as the dressed-atom blue shift. In material having a bound biexcitonic molecule, the excitonic blue shift, observed at large detuning, becomes a red shift at small detuning close to the exciton-biexciton resonance.