Threshold-controlled and compact microring resonator-based all-optical logic gates for photonic integration

This work presents the design and simulation of all-optical logic gates using microring (MR) resonator structures for integrated photonic applications. Ring resonators (RR) offer wavelength-selective filtering through resonance, enabling them to perform logic operations by controlling the coupling and interference of optical signals. The proposed structure consists of an MR coupled to dual straight bus waveguides in an add-drop configuration. Binary logic is implemented by analyzing the output optical intensity under varying input conditions, using specific threshold values to distinguish logic states. For both the logic gates, output intensity equal to or greater than 50% is considered logic ‘1’. Simulation results confirm that the MR structure accurately performs logic functions based on the constructive or destructive interference of the input signals within the resonator. Logical outputs are derived by comparing the transmitted optical power at the drop port against the defined thresholds. The device exhibits a compact footprint, and a fast response time, making it suitable for integration into photonic circuits. The implementation does not require any external tuning mechanisms, such as thermal or electro-optic control; the system still relies on sufficient optical input power to achieve nonlinear behavior. This work emphasizes the feasibility of using RR-based designs for compact, reconfigurable, and high-speed optical computing elements. It provides a foundation for future developments in all-optical integrated logic systems.