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Soliton dynamics in photonic-crystal fibers with frequency-dependent Kerr nonlinearity

We study numerically the evolution of ultrashort pulses in passive uniform photonic-crystal fibers designed such that their nonlinear Kerr coefficient γ varies considerably with wavelength. Such fibers exhibit a zero-nonlinearity wavelength in addition to the zero-dispersion wavelength. We show that soliton evolution is affected considerably by the relative locations of the zero-nonlinearity and zero-dispersion wavelengths with respect to the input wavelength. Among the features observed numerically are as follows: the enhancement or suppression of the Raman-induced redshift of fundamental solitons, amplification or suppression of a dispersive wave shed by the soliton, and the splitting of a fundamental soliton into two co-propagating solitons through a dispersive wave that forms a soliton in the normal-dispersion region because of a negative value of γ in this region.