Phenomenological Description of Light Scattering and Thermal Radiation

Summary

The connections between induced and spontaneous observable effects in a quasiequilibrium sample are discussed. A generalized Kirchoff’s law (GKL), expresssing the statisics of thermal radiation (TR) in terms of the sample’s elastic scattering matrix (SM) and the temperature, is obtained in the one-photon approximation. A similar expression describes the statistics of Raman-scattered light (including the Stokes-polariton and Stokes-antistokes correlation) in terms of the SM of the pumped sample in the parametric approximation. In the case of weak two-photon nonlinearity the 2rd, 3d and 4th moments of the TR are determined by the quadratic and cubic SM-s. It is shown that the TR of noncentrosymmetric sample should contain a stationary term <E³> cubic in the electric field. It is suggested that the relation between spontaneous and induced phenomena and peculiarities of two-photon fields may lead to metrological applications.