We propose and analyze an all-optical switching device on a nonlinear Mach–Zehnder waveguide interferometer. The nonlinear medium is modeled as a two-level system to take saturation and attenuation effects into account.
A Mach–Zehnder interferometer with a nonlinear medium in each arm is treated as an all-optical switching device. In a classical treatment, the interferometer can, in principle, operate as an ideal switch, but quantization of the electromagnetic fields limits the switching capability. In this treatment we illustrate the fundamental quantum limits that apply to switching in all-optical devices by studying the nonlinear Mach–Zehnder interferometer. In particular the input states are assumed to be coherent states and the reduction in the quality of the switching device is discussed.
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.
In this Letter, we propose and analyze a switchable integrated optical waveguide device employing a modified Mach-Zehnder interferometer, capable of generating nondegenerate, maximally spatial-mode entangled photon pairs. Using an integrated electro-optic phase modulator, we show the possibility of on-demand switching of spatial-mode entangled state from a Φ+ to a Ψ+ state and vice versa. Such a versatile device with the potential of easy manipulation of the "spatial-mode" degree of freedom, should be very interesting in realizing integrated optical chips for quantum information processing.