Nonlinear pulse propagation in long-period fiber gratings: theory and experiment

In this paper, we discuss theoretical and experimental aspects of nonlinear pulse propagation in long-period fiber gratings. We derive nonlinear coupled mode equations for co-propagating core and cladding modes in a long-period fiber grating and show that the intensity dependent index can be used to tune the mode coupling, thereby creating a mechanism for pulseshaping and all-optical switching. Extensive numerical simulations, which describe the nonlinear pulse dynamics, are compared with experiments. We discuss the application of these nonlinear effects to signal processing in all-optical fiber communications.