title: Experimental realization of photonic topological insulator in a uniaxial metacrystal waveguide.
abstract: Photonic analogue of topological insulator was recently predicted by arranging ε/μ (permittivity/permeability)-matched bianisotropic metamaterials into two-dimensional superlattices. However, the experimental observation of such photonic topological insulator is challenging as bianisotropic metamaterial is usually highly dispersive, so that the ε/μ-matching condition can only be satisfied in a narrow frequency range. Here we experimentally realize a photonic topological insulator by embedding non-bianisotropic and non-resonant metacrystal into a waveguide. The cross coupling between transverse electric and transverse magnetic modes exists in metacrystal waveguide. Using this approach, the ε/μ-matching condition is satisfied in a broad frequency range which facilitates experimental observation. The topologically non-trivial bandgap is confirmed by experimentally measured transmission spectra and calculated non-zero spin Chern numbers. Gapless spin-filtered edge states are demonstrated experimentally by measuring the magnitude and phase of the fields. The transport robustness of the edge states is also observed when an obstacle was introduced near the edge.
authors.affiliation: 1] State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China [2] Department of Physics and the Institute for Advanced Study, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
authors.forename: Shao-Ji
authors.initials: SJ
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.
authors.forename: Baocheng
authors.initials: B
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
authors.forename: Jian-Wen
authors.initials: JW
authors.lastname: Dong
authors.affiliation: Department of Physics and the Institute for Advanced Study, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: C T
authors.initials: CT
authors.lastname: Chan