Theory of Raman scattering by bulk polaritons of a composite medium

The theory of Raman scattering by bulk polaritons in a composite medium is developed. The effective dielectric function of the composite medium is modelled using the Maxwell-Garnett formulation. We apply the fluctuation dissipation theorem to obtain bulk electric field fluctuations. The differential scattering cross section for bulk polaritons is derived, and is found to have a Lorentzian lineshape. It is shown that the dispersion relation, electric field fluctuations, damping function and the differential scattering cross section are strongly dependent on the filling factor, f, which is a measure of the constituents of the composite medium. Our results are applied to a composite medium of KCI and Ag. (author)