title: Demonstration of a Three-dimensional Negative Index Medium Operated at Multiple-angle Incidences by Monolithic Metallic Hemispherical Shells.
abstract: We design and construct a three-dimensional (3D) negative index medium (NIM) composed of gold hemispherical shells to supplant an integration of a split-ring resonator and a discrete plasmonic wire for both negative permeability and permittivity at THz gap. With the proposed highly symmetric gold hemispherical shells, the negative index is preserved at multiple incident angles ranging from 0° to 85° for both TE and TM waves, which is further evidenced by negative phase flows in animated field distributions and outweighs conventional fishnet structures with operating frequency shifts when varying incident angles. Finally, the fabrication of the gold hemispherical shells is facilitated via standard UV lithographic and isotropic wet etching processes and characterized by μ-FTIR. The measurement results agree the simulated ones very well.
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Ting-Tso
authors.initials: TT
authors.lastname: Yeh
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Tsung-Yu
authors.initials: TY
authors.lastname: Huang
authors.affiliation: Metamaterials Laboratory, RIKEN, Saitama 351-0198, Japan.|RIKEN Center for Advanced Photonics, RIKEN, Saitama 351-0198, Japan.|Tokyo Institute of Technology, Kanagawa 226-8503, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC.|Department of Materials Science Center for Nanotechnology, Materials Science, and Microsystems, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Ta-Jen
authors.initials: TJ
authors.lastname: Yen