Abstract

Materials with strong nonlinearity are desirable for optical switching devices. Recent research shows that ring resonators can be used in a nonlinear Mach-Zehnder interferometer to significantly reduce the switching power [1] by increasing the nonlinear phase sensitivity. In a serially cascaded, or sequence, of resonators [2], the nonlinear sensitivity can be further improved. When taking material absorption into account, a ring resonator can facilitate a larger nonlinear phase shift and greater figure of merit than the constituent bulk material [3]. However, this arrangement produces an intensity transmittance that is non-ideal for a general purpose phase shifting element. We show that a simple modification to the serially-cascaded microring (CMRR) configuration - adding an extra output port on the top of the last ring – facilitates a enhanced nonlinear sensitivity, a large saturating phase shift, and nearly ideal intensity transmittance characteristics even if the material itself has large linear and two-photon absorption.

© 2002 Optical Society of America