Additional-boundary-condition-free theory of an exciton polariton in a slab

Abstract

The electric field associated with an exciton polariton in a slab of spatially dispersive medium has been calculated ‘‘from first principles’’ according to the general framework by Cho in which the argument of additional boundary condition (ABC) is completely avoided. As the exciton wave function, we have considered, in addition to the bulk component, the distortion of the type exp(-PZ) near the surfaces according to the analytic model of D’Andrea and Del Sole, and the slab thickness d has been assumed to satisfy exp(-Pd)≪1. The result has been shown to be equivalent to that obtained from the explicit use of ABC on the same model. In this way, it is demonstrated that the ABC-free formalism is not only of conceptual, but also of practical, use.