Directional coupling in a twin core photonic crystal fiber using heat treatment

Summary form only given. Multicore fibers are optical fibers with two or more cores. The cores can be coupled or uncoupled depending on the properties of the fiber. Photonic crystal fiber (PCF) is an undoped all silica fiber with an array of air holes that run along its length. This novel type of optical fiber has some remarkable waveguiding properties that can be characterized by the size of the air holes and the distance between them. PCF is fabricated using a proven stack and draw technique, due to this unique fabrication process the inclusion of multiple cores, anywhere within the two-dimensional hexagonal lattice is significantly simpler than the fabrication of conventional step index fibers. In this paper we demonstrate an evanescent field coupler by selective heat-treating a region of a previously uncoupled twin core PCF.