Temporal dynamics of parametric transformation in a Raman-active medium with the induced rotational coherence

The collinear generation of radiation with a multicomponent spectrum is obtained upon scattering of picosecond pulses in gaseous hydrogen coherently excited by the pulsed biharmonic pump in resonance with the Raman-active rotational S₀(1) transition. Probe pulses at 355 nm were almost completely transformed to the radiation with the multicomponent spectrum of width ~5000 cm^-1 and the components spaced by 587 cm^-1. The solution of a system of equations for the four-photon Raman – parametric interaction is obtained in the plane-wave dispersionless approximation in the spectral and time representations. The equations describe the transformation of probe pulses in gas with the induced coherence into an arbitrary number of interacting spectral components. The consideration performed in the second order of the dispersion theory provides good agreement with experiments on the transformation into different spectral components depending on the probe-pulse delay.