Influence of fiber birefringence on orthogonal Raman scattering and soliton trapping in photonic crystal fibers

We demonstrate the effects of fiber birefringence on soliton trapping in two highly birefringent photonic crystal fibers. Linearly polarized ultrashort pulses are injected into the fiber in an anomalous dispersion regime, resulting in the generation of a soliton and a trapped pulse amplified through orthogonal Raman gain. The two orthogonally polarized pulse components are located at group-velocity matched wavelengths. Higher fiber birefringence leads to a larger polarization extinction ratio and greater spectral separation of pulse components. For a certain range of the input field polarization azimuth angles, the pulse components walk off in a more birefringent fiber, which prevents the formation of a single pulse. The experimental results are supported by numerical simulations.