Propagation through apodized gratings

It is shown that light propagation in an apodized fiber Bragg grating with a Kerr nonlinearity approximately obeys a nonlinear Schrodinger-like equati on, but with extra terms because the eigenstates of the grating vary with p osition. It is shown that propagation through such a grating leads to field enhancement, and to a nontrivial phase shift; an approximate expression fo r the reflectivity is also found. (C) 1998 Optical Society of America.