Impact of the wavelength dependence of the mode field on the nonlinearity coefficient of PCFs

We theoretically analyze the impact of the wavelength dependence of the optical mode-field distribution on the nonlinearity coefficient γ for photonic crystal fibers with square and hexagonal air-hole lattices and for a silica rod. For the core size, which provides the maximum achievable nonlinearity coefficient, the relative change of γ over a 60-nm wavelength range around 1550 nm amounts to approximately 12.5%.