Statistical characteristics of backward stimulated Raman scattering due to quantum noise

We investigate statistical characteristics of forward and backward scattering caused by quantum noise of polarization of a medium in a chamber with hydrogen pumped by focused laser radiation. Calculation is performed both with and without allowance for the generation of the anti-Stokes wave in parametric Stokes-anti-Stokes interaction. It is demonstrated that, under definite intensities of pump radiation, the probabilities of energy distribution in backward and forward scattering become bimodal.