All-optical half-subtractor based on photonic crystals

A two-dimensional photonic-crystal-based structure was used for designing a novel structure for realizing an all-optical half-subtractor. The proposed structure was designed by combining the phase shift keying technique with the optical beam interference mechanism. The proposed structure works completely in the linear region, and therefore it does not require a high amount of optical power. The delay time for the proposed structure is about 2 ps.