Some nonlinear integrated optical devices

Nonlinear integrated optical devices have been widely investigated in the last decade due to the possibility of realising all optical devices. Two classes of nonlinear devices are discussed: directional couplers as spatial filtering and as wavelength filtering devices, and spatial selection of the beam, by the help of spatial soliton interaction in the waveguide. These devices are analyzed assuming a third order nonlinear material. A discussion of the cubic behaviour of a second order nonlinear material is also included, considering in particular the wavelength filtering properties of the directional coupler