All-optical switching of light in a multiple quantum well waveguide arising from the nonlinear coupling of two TE guided modes

Multiple quantum well (MQW) layers have an enhanced nonlinear refractive index which can be exploited in order to achieve all-optical switches/modulators. The authors demonstrate a switching device which makes use of the beating between the fundamental guided mode and a higher order mode of a MQW waveguide to achieve a large ON/OFF ratio. A closely coupled vertical coupler switch which consists of two GaAlAs waveguides separated by a MQW region has already been reported. Theoretical analyses of the nonlinear coupling between modes of such a waveguide have predicted that switching can indeed be achieved