Parametric and Raman amplification in photonic crystal fiber

We study the interplay between parametric and Raman gain in photonic crystal fibers by taking into account the vector nature of the electric field, the fiber frequency dependent birefringence, the Kerr nonlinear coefficient, the Raman gain profile and chromatic dispersion. In particular, we show that an accurate representation of the frequency dependence of the nonlinear and dispersive properties of a photonic crystal fiber is essential for correctly describing the overall gain profile for a probe signal at large frequency detuning from a continuous wave or pulsed pump. For example, we found that fourth and higher order dispersion have a striking influence on the spectrum of modulation polarization instability gain in both the high and low birefringence regime, in that the vector parametric gain is suppressed above a critical level of linear birefringence. We validated the theory by experimental observations of vector parametric amplification in high birefringence holey fiber with triple defects.