An introduction to guided-wave nonlinear ultrafast photonics

We present a general theoretical framework for describing ultrashort pulse propagation in optical fibers and discuss the conditions for the generation of spatiotemporal bullets and multimode solitons. We compare theory with recent experiments involving the generation of multimode solitons in graded-index multimode optical fibers. This reveals the formation of walk-off solitons, where nonlinearity compensates for both chromatic and modal dispersion, as well as the irreversible attraction of multimode solitons to the fundamental mode of the fiber for long propagation distances.