POLARITON VERSUS OPTICAL STARK-EFFECT - AN OLD CONCEPT REVISITED

The recently observed optical Stark shift of the exciton has been shown to result only from interactions between excitons and the effect is proportional to the laser intensity. On the other hand, in the well-known polariton effect, excitons are assumed to be pure non-interacting bosons and the effect is independent of the laser intensity. These two effects which both deal with photons acting on a semiconductor, appear contradictory. We show that they are in fact two limits of the same phenomenon. One consequence is a photon velocity varying also with laser intensity in the optical Stark effect regime. © 1990.