Raman scattering of light by coherent polaritons

A theory is presented of the active speetroscopy using steady-state spontaneous Raman scattering by polaritons, i.e., spontaneous Raman scattering of a "test" wave ω_π by polaritons generated in an independent process of polariton stimulated Raman scattering of a given high-power pump wave ω₁ with a possible additional illumination at the frequencies of polariton ω_π and/or Stokes ω_s =ω_π–ω_p waves. A fluctuation-dissipation method is used to find the intensities of the scattered waves at frequencies ω_a,σ = ω_π ±ω_p. The cases of weak and strong absorption at a frequency ω_p are considered and various regimes are discussed. A detailed analysis is made of the interference of three- and four-photon mechanisms of the formation of scattered waves. The possibility of the active speetroscopy based on the spontaneous Raman scattering by polaritons in certain spectroscopic measurements is discussed.