Piecewise linear integrated optical device as an optical isolator using two-port nonlinear ring resonators

A nonlinear (piecewise linear) optical transfer function for optical applications, generally, is introduced. A realization method for the proposed block based on two-port nonlinear ring resonators array is presented. Optical isolation as a special application is investigated. Effect of system parameters on transfer function is considered. The introduced nonlinear device parameters such as threshold and slope of linear part can be controlled using coupling coefficients and ring lengths. We show that using our proposed idea easily more than 30-dB isolation can be obtained only with two rings. Also, the proposed idea easily can be integrated with semiconductor lasers as well as other integrated devices and systems. Finally the analytical result for approximation of the threshold and slope of linear part is presented.