Nonlinear propagation in slow-light states of high-index photonic crystal fibers (PCFs) is studied numerically. To avoid divergencies in dispersion and nonlinear parameters around the zero-velocity mode, a time-propagating generalized nonlinear Schrödinger equation is formulated. Calculated slow-light modes in a solid core chalcogenide PCF are used to parameterize the model, which is shown to support standing and moving spatial solitons. Inclusion of Raman scattering slows down moving solitons exponentially, so that the zero-velocity soliton becomes an attractor state. An analytical expression for the deceleration rate that compares favorably with the numerical results is derived. Collisions of successive solitons due to the Raman deceleration are studied numerically, and it is found that the soliton interaction is mostly repulsive, as expected from the established theory of fiber solitons.
Optical Society of America. Journal B: Optical Physics, 2011, Vol 28, Issue 1, p. 37-44