Realization of Ultra-Accurate and Compact All-Optical Photonic Crystal OR Logic Gate

By unique combination of single-line defects, Mach-Zehnder interferometer, and ring resonators, we propose a novel, easy-to-fabrication and linear scheme for realizing accurate and compact all-optical OR logic gate based on 2-D photonic crystal structures. To obtain the transmission spectra of the structure, we considered the entire structure as a single cavity and then we applied a fast Fourier transform to the transmitted spectral power densities at the output port and the unexcited input port; this strategy enhances the control on unwanted port-to-port power reflections and hence increasing the distinction between logic levels. Simulating the electromagnetic wave propagation in the proposed device reveals that the accurate all-optical OR logic gate is obtained. The achieved contrast ratio between logic levels is similar to 7.27 dB. Moreover, since all ports are located on the same side and the size of the structure is 12.5 mu m x 16 mu m. It is fully compacted and has the ability of dense integration. The proposed structure is completely easy-to-fabrication and designed for using in future high accuracy photonic integrated circuits.