title: Creation of large band gap with anisotropic annular photonic crystal slab structure.
abstract: A two-dimensional anisotropic annular photonic crystal slab structure composed of circular air holes and dielectric rods with finite thickness in a triangular lattice is presented to achieve an absolute photonic band gap. Positive uniaxial crystal Tellurium is introduced to the structure with the extraordinary axis parallel to the extension direction of rods. The role of each geometric parameter is investigated by employing the conjugate-gradient method. A large mid-gap ratio is realized by the parameter optimization. A flat band called as anomalous group velocity within two large gaps is discovered and can be widely applied in many fields. A hybrid structure with GaAs slab and Te rods is designed to achieve a large gap and demonstrates that the annular structure can improve the gap effectively.
authors.affiliation: Key Laboratory of Quantum Information, China Academy of Science, Hefei, Anhui 230006, China .
authors.forename: Peng
authors.initials: P
authors.lastname: Shi
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
authors.forename: Xue-liang
authors.initials: XL
authors.lastname: Kang
authors.forename: Yong-ping
authors.initials: YP
authors.lastname: Li