Coupling between photons and exciton polaritons across surfaces of direct-gap semiconductors

Abstract

The coupling between external photons and bulk exciton polaritons is investigated theoretically in the case of an appropriate repulsive surface potential for the exciton motion. The analysis of the limitations of the Hopfield-Thomas model indicates that it gives too large values of the lifetime broadening or the longitudinal-transverse splitting. The calculated effective dead-layer thicknesses to be expected in fitting the Hopfield-Thomas model to experiments agree well with experimental results also in the case of very small oscillator strengths giving thick dead layers.