An InGaAsP/InP 2×2 Mach-Zehnder interferometer(MZI) optical switch based on multimode interference(MMI) couplers is presented.The switch characteristics are simulated using a three-dimensional beam propagation model.The switch structure is designed to be single mode operation and insensitive to polarization.When injected current gives rise to a change in the refractive index and causes a π-phase shift,the light is routed to the bar port resulting in space switching of the signal.The light signal...