ABSTRACT

This chapter explains a more general phenomenological approach to formulate a generalized Kirchhoff law for a Raman scattering process that includes parametric effects and from which follows, in particular, the existence of a statistical connection between the Stokes and anti-Stokes scattering fields. From the macroscopic point of view, hyperparametric scattering can also be described in terms of the nonlinear polarizability of the medium. As the intensity of the pump increases, the linear and quadratic dependences on the pump change into an exponential dependence, which corresponds to stimulated Raman scattering and "hyperparametric superluminescence." The existence of mutual correlation between the Stokes and anti-Stokes frequency components of the Raman scattering field can readily be substantiated with a classical modulation model of Raman scattering. A two-beam pump—in particular, a standing wave—can be used for the spatial separation of correlating fields in the case of quasielastic scattering.