All-optical 3-input OR and 2-input AND/NIMPLY logic gates in a linear planar three-core optical fiber coupler

Most all-optical logic processing devices reported in the literature rely on nonlinear effects, which increase implementation complexity and hinder scalability in larger optical circuits. In this work, we present the numerical modeling of two all-optical logic gates based on a fully linear, dispersion-free planar symmetric three-core optical fiber coupler. The devices operate with low-power amplitude-modulated pulses and require no nonlinear materials or mechanisms. By exploiting only the fiber geometry and coupled-mode theory, we demonstrate two logic processing functionalities: a 3-input OR gate and a configurable logic gate that performs either the AND or the NIMPLY operation, selected by a control signal. The proposed devices exhibit clear logical discrimination according to a contrast-based performance metric and feature simple structures that favor compact implementations and integration into larger linear photonic architectures.