Application of photonic-crystal-based nonlinear ring resonators for realizing an all-optical comparator

Optical comparators can play crucial roles in the all-optical digital circuits required for optical calculation and optical processing. A typical digital comparator is a logic circuit that can compare two binary codes and show the results by activating one of its three output ports. In this paper, a photonic crystal (PhC)-based structure was proposed for designing a 1-bit all-optical comparator. The proposed structure was designed using nonlinear ring resonators inside PhCs. Optical intensity of ${1}\,\,{\rm W/}\unicode{x00B5} {{\rm m}^2}$1W/µm² at the input ports is required for the proper operation of the proposed structure. For the final structure, the maximum rise time obtained was about 4 ps.