The theory of Raman scattering by surface polaritons

The fluctuation–dissipation theory of spontaneous Raman scattering (RS) by surface polaritons (SP) is carried out. The appearance of scattering emission is treated as the result of mixing of the pump emission and the fluctuating surface electromagnetic field. A calculation is made of the surface electromagnetic fluctuations near the interface between the two dissipative media and in the absorbing layer surrounded by transparent dielectrics. Expressions are found and analysed describing the frequency–angular distribution of the scattering emission intensity in the layer, taking into account the interference of SP localized near different surfaces (and near the interface of two absorbing media). The RS intensities are expressed by the phenomenological parameters of the media. It is also shown that the RS intensity decreases essentially with increasing scattering angle θ (when the scattering frequency approaches the frequency of the surface phonon) due to the increasing localization of SP. Various essential physical features of the phenomenon are analysed in detail: scattering line shape and its angular dependence; the Fermi resonance of SP and its display in the RS; mixing of SP of different media and RS by appearing mixed modes; RS by SP connected genetically with the linear medium which borders with the transparent nonlinear medium; evolution of RS in a layer by decreasing its thickness, and others. [Russian Text Ignored.]