Hidden-symmetry-enforced nexus points of nodal lines in layer-stacked dielectric photonic crystals  

作　　者：Zhongfei Xiong Ruo-Yang Zhang Rui Yu C.T.Chan Yuntian Chen 

机构地区：[1]School of Optical and Electronic Information,Huazhong University of Science and Technology,Wuhan 430074,China [2]Department of Physics,The Hong Kong University of Science and Technology,Clear Water Bay,Hong Kong,China [3]School of Physics and Technology,Wuhan University,Wuhan 430072,China [4]Wuhan National Laboratory of Optoelectronics,Huazhong University of Science and Technology,Wuhan 430074,China

出　　处：《Light(Science & Applications)》2020年第1期315-324,共10页光（科学与应用)（英文版）

基　　金：supported by the Natural National Science Foundation(NSFC)(Grant No.11874026);the Research Grants Council of Hong Kong,China(Grant Nos.AoE/P-02/12 and 16304717).

摘　　要：It was recently demonstrated that the connectivities of bands emerging from zero frequency in dielectric photonic crystals are distinct from their electronic counterparts with the same space groups.We discover that in an AB-layerstacked photonic crystal composed of anisotropic dielectrics,the unique photonic band connectivity leads to a new kind of symmetry-enforced triply degenerate points at the nexuses of two nodal rings and a Kramers-like nodal line.The emergence and intersection of the line nodes are guaranteed by a generalized 1/4-period screw rotation symmetry of Maxwell’s equations.The bands with a constant kz and iso-frequency surfaces near a nexus point both disperse as a spin-1 Dirac-like cone,giving rise to exotic transport features of light at the nexus point.We show that spin-1 conical diffraction occurs at the nexus point,which can be used to manipulate the charges of optical vortices.Our work reveals that Maxwell’s equations can have hidden symmetries induced by the fractional periodicity of the material tensor components and hence paves the way to finding novel topological nodal structures unique to photonic systems.

关 键 词：SYMMETRY NODAL DIELECTRIC 

分 类 号：O17[理学—数学]