| Abstract: | The semiclassical equations of SRS are derived by the following method: The many-level molecule is described by the Schrödinger equation and subsequently all amplitudes but those of the essential two levels are eliminated by approximate integration. Especially the case of equal group velocities for pump and Stokes wave is considered. Terms describing a frequency shift due to dynamical Stark effect and a change of refraction index by vibrational excitation can be removed by a suitable transformation. Under various, physically different, assumptions the system of molecular and field equations is reduced to the equations describing a quasimonochromatic pulse propagating in a resonant two-level system, and in this way we can find a rich manifold of solutions. E.g., the 2π-pulse of self-induced transparency can be transferred to SRS. By other assumptions we are led to equations defining the Bäcklund transformation for the sine-Gordon equation. For this case also soliton type solutions can be constructed. |
