The apolicability of nonlinear organic materials in integrated optics is discussed theoretically. We have studied the properties of an optically linear waveguide covered with a nonlinear organic film. Optical switching, power limiting and thresholding in optical logic are potential applications of this structure.
The field distribution and propagation constant are solved exactly. The field in the nonlinear film is written in terms of Jacobian elliptic functions, and a procedure to compute them is presented. The trial functions used here turn out to be flexible and useful because – in contrary to the approaches where hyperbolic functions are used – they lead to a solution for a variety of parameters and in the case of negligible nonlinearity it coincides well with the linear case.
The method is applied to a Si3 N4 waveguide with an organic overlayer. The effect of device parameters like refractive indices, thickness of the layers, incident power and strength of the nonlinearity is studied. The intensity dependence of the wavevector is determined and the lower limit cutoff powers for some structures are calculated.