Ultra-compact photonic crystal couplers for optical switches based on band-edge resonance

Optical couplers play an important role in optical switches to split or combine light power in a predictable way. We proposed a novel scheme of photonic crystal (PhC) couplers relying on the unique characteristics of band-edge resonance. Stretched fundamental resonance can be excited in a square array of several periods to realize efficient transverse scattering. Two types of 1 × 2 and 2 × 1 PhC-couplers have been designed. The iconic features of ultra-compact constructure, ideal 3 dB splitting, and constant phase shift of 0/π prove the PhC-couplers are appropriate for splitters, combiners, and optical switches. Both numerical and experimental results validate that this PhC-coupling optical switch exhibits significant switching performances over a large variation of structural parameters. This work will be of interest for the development of optical components integration in micro-nano photonic circuits and related applications. Two types of 1 × 2 and 2 × 1 photonic crystal couplers have been proposed relying on stretched fundamental resonance near the photonic band edge. The iconic features of ultra-compact structure, ideal 3 dB splitting, and constant phase shift prove they are appropriate for the designs of splitters, combiners, and optical switches in optical components integration.