Propagation of nonlinear pulses in chirped fiber gratings

The propagation of nonlinear optical pulses in chirped fiber gratings is st udied. The dynamics is analyzed on the basis of the inhomogeneous nonlinear Schrodinger equation. By using perturbation theory we demonstrate that the inhomogeneity affects the amplitude and the width, as well as the phase an d the velocity of the soliton. The dynamics of a multisoliton pulse (breath er) in chirped gratings is also discussed. It is shown that the velocity va riation of individual solitons leads to the breaking of a bound multisolito n state. This process manifests itself as the pulse splitting that is exper imentally observed by other authors. Numerical. simulations of the pulse dy namics agree well with analytical results for wide range of parameters.