Raman-assisted parametric frequency and polarization conversion in a birefringent fiber

Highly efficient energy conversion of the pump into the downshifted parametric Stokes radiation resulting from the phase-matched parametric four-photon mixing and subsequent perpendicular Raman amplification in a birefringent fiber is presented. We also observed significant polarization conversion from the fast y axis to the slow x axis of the birefringent fiber as a consequence of group-velocity-matched perpendicular Raman amplification of the x-polarized parametric Stokes radiation by the y-polarized pump.