Intrinsic in-plane nodal chain and generalized quaternion charge protected nodal link in photonics  

作　　者：Dongyang Wang Biao Yang Qinghua Guo Ruo-Yang Zhang Lingbo Xia Xiaoqiang Su Wen-Jie Chen Jiaguang Han Shuang Zhang C.T.Chan 

机构地区：[1]Department of Physics,Hong Kong University of Science and Technology,Hong Kong,China [2]College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha,China [3]Institute for Advanced Study,Hong Kong University of Science and Technology,Hong Kong,China [4]Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education,School of Physics and Electronics,Hunan University,Changsha,China [5]Institute of Solid State Physics and Department of Physics,Shanxi Datong University,Datong,China [6]School of Physics&State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-Sen University,Guangzhou,China [7]Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering,Tianjin University and the Key Laboratory of Optoelectronics Information and Technology(Ministry of Education),Tianjin,China [8]School of Physics&Astronomy,University of Birmingham,Birmingham,UK

出　　处：《Light(Science & Applications)》2021年第5期881-889,共9页光（科学与应用)（英文版）

基　　金：This work is supported by the Research Grants Council of Hong Kong,China(AoE/P-02/12,16304717,16310420);the Hong Kong Scholars Program(XJ2019007);W.-J.C.is supported by the National Natural Science Foundation of China(Grant no.11874435);J.H.is supported by the National Natural Science Foundation of China(Grant no.62025504,61935015);S.Z.acknowledges support from the ERC Consolidator Grant(TOPOLOGICAL),the Royal Society,and the Wolfson Foundation.

摘　　要：Nodal lines are degeneracies formed by crossing bands in three-dimensional momentum space.Interestingly,these degenerate lines can chain together via touching points and manifest as nodal chains.These nodal chains are usually embedded in two orthogonal planes and protected by the corresponding mirror symmetries.Here,we propose and demonstrate an in-plane nodal chain in photonics,where all chained nodal lines coexist in a single mirror plane instead of two orthogonal ones.Nodal lines are degeneracies formed by crossing bands in three-dimensional momentum space.Interestingly,these degenerate lines can chain together via touching points and manifest as nodal chains.These nodal chains are usually embedded in two orthogonal planes and protected by the corresponding mirror symmetries.Here,we propose and demonstrate an in-plane nodal chain in photonics,where all chained nodal lines coexist in a single mirror plane instead of two orthogonal ones.The chain point is stabilized by the intrinsic symmetry that is specific to electromagnetic waves at theГpoint of zero frequency.By adding another mirror plane,we find a nodal ring that is constructed by two higher bands and links with the in-plane nodal chain.The nodal link in momentum space exhibits non-Abelian characteristics on a C_(2)T-invariant plane,where admissible transitions of the nodal link structure are determined by generalized quaternion charges.Through near-field scanning measurements of bi-anisotropic metamaterials,we experimentally mapped out the in-plane nodal chain and nodal link in such systems.The chain point is stabilized by the intrinsic symmetry that is specific to electromagnetic waves at the r point of zero frequency.By adding another mirror plane,we find a nodal ring that is constructed by two higher bands and links with the in-plane nodal chain.The nodal link in momentum space exhibits non-Abelian characteristics on a C2T-invariant plane,where admissible transitions of the nodal link structure are determined by generalized quaternion charges.Through

关 键 词：NODAL plane MIRROR 

分 类 号：O43[机械工程—光学工程]