Discrete optical multistability in the system of coupled nonlinear waveguide resonators

Self-action of the field of a waveguide mode (SFWM) due to quadratic nonlinearity is of interest for creating structures with controllable parameters. We solve this problem for the general case of an asymmetric waveguide (AW), whose layers have different nonlinear coefficients. We show that under SFWM conditions there arises a variation in the effective refractive index (ERI) and the effective cross section (ECS) of the mode, which depending on the waveguide parameters and the ratio of the coefficients of the layers nonlinearities, leads to either focusing or defocusing of the optical flux in the waveguide. Applying this result to the investigation of multistability, appearing in a system of the coupled nonlinear waveguide resonators, we can obtain desired discrete optical multistability.