Dispersion control in square lattice photonic crystal fiber using hollow ring defects

We propose a new dispersion control scheme by introducing hollow ring defects having a central air hole and a GeO₂-or F-doped silica ring with in a square lattice photonic crystal fiber. We confirmed the flexible dispersion controllability in the proposed structure in two aspects of dispersion managements: ultra-flattened near-zero dispersion in the 530nmbandwidth over all communication bands and dispersion compensation in C, L, and U band with a high compensation ratio of 0.96∼1.0 in reference to the standard single mode fiber. The proposed SLPCFs were also estimated to have an inherently low splice loss due to the index contrast between the doped-ring and silica that kept a good guidance even along with collapsed air holes, which cannot be achieved in conventional PCFs.