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

Abstract

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 $\sim 7.27$ dB. Moreover, since all ports are located on the same side and the size of the structure is $12.5~\mu \text{m} \times 16~\mu \text{m}$ . 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.