The effect of light scattering in cavity electrodynamics: Fresnel equations with decoherence

We consider the effect of light decoherence in a Fabry-Perot microcavity. We show that, when present, it may significantly change the linear response to the incident light. The optical properties of the bounding mirrors are described using classical electrodynamics, and the light scattering causing the phase breaking is treated as a multichannel scattering problem employing a model introduced by Büttiker to describe dephasing in electron transport. We show that the dephasing causes a gradual erosion of the cavity photon mode and thus impedes the formation of molecular polaritons. Consequently, the polariton signatures in the transmission and absorption optical spectra of the microcavity fade away as the scattering intensifies.