Optical logic operations using a meshed Mach-Zehnder interference array

Optical logic operations play a significant role in digital optical computing and signal processing. Conventional logic operations always rely on nonlinear light-matter interactions, where high energy consumption, restricted logical function, and poor cascadability seriously hamper their practical application. In this study, we introduce a meshed Mach-Zehnder interferometer (MZI) array to provide a complex linear-modulation solution for optical logic operations. The optical interference unit (OIU) is formed by a meshed MZI array, and the unitary matrix-vector product operations are imitated. The introduction of a linear vector composition makes it possible to optimize the phase-shift parameters of the OIU using a gradient descent algorithm for non-unitary logic operations. In the simulation, we demonstrate that seven basic logic operations are well implemented by an OIU with three MZIs. Complex logic operations and multi-input logic operations are also achieved by cascading basic components and increasing the size of the OIU. These linear-optical logic operations are implemented on the same platform using phase-only modulation, which has low power consumption and is critical for device fabrication and system integration.