Polariton excitation rates from time dependent dielectrics

Abstract

We apply time dependent perturbation theory to a general class of problems involving time dependent dielectric media in cases where dissipation cannot be ignored. The theory is used to derive polariton excitation rates in three illustrative cases, including that of a travelling Gaussian perturbation to the susceptibility of an otherwise infinite homogeneous dielectric. We find that the excitation rate is increased when the wave-vector and frequency of each polariton in the pair is close to satisfying either the dispersion relation for electromagnetic waves, or is close to a material resonance. We thus predict that the time dependence of a medium can excite a pair of polaritons, only one of which may appear as a propagating electromagnetic wave.