Modeling of nonlinear pulse propagation in periodic and quasi-periodic binary long-period fiber gratings

A generalized transfer-matrix method is used to model nonlinear pulse propagation in a binary long-period fiber grating (LPFG). Two interface matrices are used to describe power coupling at the heterointerfaces, as in the linear case. Nonlinear phase shifts and pulse dispersion through the two basic regions are modeled by coupled nonlinear Schrodinger equations. Based on the generalized transfer-matrix model, a local intensity-dependent detuning parameter is introduced with which we investigate the general conditions for complete switching. Nonlinear switching in a quasi-periodic Fibonacci LPFG is also studied, and it is shown that complete switching can be achieved in such a quasi-periodic grating. (C) 2002 Optical Society of America.