Nonlinear thin-layer theory and approximative techniques

We derive a thin-layer theory for stratified nonlinear structures. By using a superposition of plane waves we solve the Kerr-Maxwell equation rigorously within a thin slab. We construct the characteristic matrix of the medium and show that the wave vectors became field dependent. We also consider alternative analytical methods that can be employed in layered nonlinear structures. Especially we make use of the calculus of variations and Hamilton's canonical perturbation theory.