Some features of the use of active spectroscopy in the case of inverse Raman scattering of a pump doublet

Sources of distortion of the information obtained by active Raman spectroscopy are discussed. The case of a strong nonlinear coupling between pump waves due to the inverse Raman scattering is analyzed in detail. Active spectra are calculated for the case of inverse Raman scattering of a pump doublet which occurs when the nonlinear interaction length is increased. A criterion is derived of the strength of the nonlinear coupling between pump waves which ensures that the inverse Raman scattering does not distort the dispersion curves of the nonlinearity deduced from active spectroscopy data.