Cavity photons and Coulomb excitons

In this subsection we introduce some notations for the bare excitations whose interaction leads to the formation of cavity polariton states. These bare excitations are cavity photons and Coulomb excitons. 

We start with the notation for the cavity photon modes considering the solutions of Maxwell s equations for an isotropic microcavity. Let Lc be the microcavity thickness, and ec the dielectric constant of the microcavity nonres- 

Now let us consider the fields in a microcavity made from an anisotropic organic crystal with excitonic resonances. We suppose that the microcavity is a slab of an organic crystal surrounded by ideal mirrors. The system of Maxwell s equations is  

To proceed, one has to know the dielectric tensor ejfc(w). It can be found either from experiment, or with the help of a microscopic theory. Below we recall several useful facts concerning the relation existing between the excitonic resonances and the dielectric tensor in organic crystals (see also Chs. 2 and 3). 

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