Modeling and anatomization of three-input photonic crystal-based XOR/XNOR gates for photonic integrated circuits

The optimized representation of an effective all-optical 3-input XOR/XNOR gate is designed with T-shaped 2-D photonic crystals (PhC) composed of silicon (Si) material embedded in an air background. Both XOR/XNOR logic gates are implemented in a single layout, with a phase change between the input signals applied. The beam interference concept is used to design the layout and simulation results are evaluated using finite-difference-time-domain (FDTD) method. This layout has a contrast ratio (CR) of 13.37 dB and 11.81 dB for XOR and XNOR gates respectively. Several other parameters such as response time, transmission efficiency, insertion loss etc., are calculated resulting in good outputs by optimizing the radius and refractive index that can be employed in photonic integrated circuits.