Significantly enhanced birefringence of photonic crystal fiber using rotational binary unit cell in fiber cladding

We propose a novel high-birefringence index-guiding photonic crystal fiber (PCF). This PCF is composed of a solid silica core and a cladding with rotational squeezed-triangular-lattice elliptical air holes, which consist of binary unit cells. The birefringence of a fundamental mode in such a PCF is analyzed numerically using the finite element method. A binary unit cell in a PCF cladding that combines its rotational effects can enhance the birefringence as high as a magnitude of the order of 10-2. This study provides a new viewpoint for the characterization and design of a high-birefringence PCF. © 2007 The Japan Society of Applied Physics.