Wideband optical logic gates based on a 3×3 multi-mode interference coupler

In this paper, an all-optical logic gate with multiple functions and asymmetric structure is theoretically designed and simulated using a silicon on insulator (SOI)-based multimode interference (MMI) coupler. By switching the optical signal to different input waveguide ports, the device can function as an OR, NOT, NAND, or NOR gate simultaneously or individually. Simulation results by using three-dimensional beam propagation method (3D-BPM) incorporated with effective index method (EIM) show that these logic gates can operate with low loss in a wide wavelength band as much as 100 nm. It is a kind of promising device for applications on the next-generation high-speed, compact logic circuits, ultrafast signal processing as well as future silicon photonics-based integrated circuits.