EIT-based MZ-MMI all-optical switch

We propose a new control structure for all-optical switching in multimode inference (MMI)-based Mach–Zehnder interferometer (MZI) devices. This structure is composed of an MZI doped by three-level nanocrystals for the realization of electromagnetically induced transparency (EIT) in the lower arm. We use two different intensities of control field for two states of the proposed switch. Using a control field in both of the two switching states is necessary, where the EIT region is transparent. By changing the intensity of the control field, the refractive index of the doped region changes, which makes the phase difference between the two arms of the MZI. Hence, the switching operation takes place. Simulation results show that the extinction ratio of the device is −32dB in the worst case.