NONLINEAR SCHRODINGER-EQUATION FOR OPTICAL MEDIA WITH QUADRATIC NONLINEARITY

Wave propagation in optical media with strong dispersion and weak quad ratic nonlinearity is analyzed using the method of multiple scales. Th is method shows that the evolution of the envelope for a single nondep leted pump wave is described by the nonlinear Schrodinger equation. He nce various self-modulation effects, due to an effective intensity-dep endent refractive index, are possible to observe in materials with qua dratic nonlinearity. That is, materials that are known to generate X(( 2)) wave processes may also support, for example, soliton propagation. Physical conditions and numerical examples are given for observing so litons, self-defocusing, and spectral broadening. Other self-modulatio n effects are also discussed as well.