Design and analysis of all-optical logic NOR gate based on linear optics

A new design of all-optical logic NOR gate has been proposed in this article based on linear optics. The logic gate has been designed on a two-dimensional holes-in-slab triangular lattice Photonic Crystal structure. Two optical bias signals, each having half unit power have been used to achieve high optical logic state at zero input condition. Finite slab height has been considered to design the proposed device. The Plane Wave Expansion method has been used to calculate the complete photonic band structure of the crystal and projected band of the waveguide. Finite Difference Time Domain method has been applied to measure and evaluate the performance of the device. The simulation results have exhibited high contrast ratio in order of 8.5 dB considering the worst-case scenario. The proposed NOR gate has been implemented as logic inverter and the noise margin of the proposed inverter has also been calculated as 630 µw² using Maximum Product Criterion. Finally, the small footprint area of the proposed device, 280 µm² and its high operating performance make the device suitable for on-chip photonic integrated circuit applications.