MZ-MMI-based all-optical switch using nonlinear coupled waveguides

We propose an all-optical switch (AOS) based on Mach–Zehnder (MZ) and Multi-mode interference (MMI) using nonlinear closely coupled waveguides. The device operates by switching between two states of coupled waveguides. In first state the refractive index of waveguides are same and light field will completely couple to nonlinear waveguide in half length of coupler and will back in the second half. We will have π phase difference in this procedure and the input field will appear in Bar-state output. In the second state the refractive index of nonlinear waveguide increase with high intensity control field. In this case, we have lower coupling and change in phase. But, we choose the best refractive index change to obtain the phase change of multiple of 2π necessary for Cross-state in output. The beam propagation method is used to simulate the device operation.