Influence of parametric four-wave mixing effects on stimulated Raman scattering in bimodal optical fibers

We analyze stimulated Raman scattering in normally dispersive bimodal fibers under single-frequency pumping conditions. Experiments show that whenever the interacting nonlinear waves propagate in the ${\text{LP}}_{01}$ and ${\text{LP}}_{11}$ modes, a parametric four-wave mixing enters unavoidably into play in the wave-coupling behavior, which causes qualitatively different phenomena compared with the ordinary process of Raman scattering, such as the parametric suppression of the first-order Raman Stokes radiation.