Method for isolating weak stimulated Raman scattering lines by selective absorption of the strongest Stokes component

The spectrum of the stimulated Raman scattering usually contains only the component characterized by the strongest gain. Its appearance results in such a strong depletion of the laser excitation that other Raman scattering signals fail to reach the sensitivity threshold of the detector. Selective absorption of this strongest component can make it easier to observe other Raman scattering lines. It is shown theoretically that the threshold for the detection of the weaker components can be lowered by a factor of seven it we use an absorbing liquid for which the absorption coefficients at the frequency of the first Stokes component and at the laser frequency are in the ratio 100:1.