Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC.
Metamaterials Laboratory, RIKEN, Saitama 351-0198, Japan.
Sci Rep. 2017 Apr 7;7:45549. doi: 10.1038/srep45549.
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.
我们设计并构建了一个由金半球壳组成的三维（3D）负折射率介质（NIM），以替代在太赫兹间隙处同时具有负磁导率和介电常数的分裂环谐振器和离散等离子体线的集成。在所提出的具有高度对称的金半球壳中，TE 和 TM 波在 0°至 85°的多个入射角下都保持了负折射率，这进一步通过动画场分布中的负相流得到证实，并且在改变入射角时胜过具有工作频率偏移的传统鱼网结构。最后，通过标准的紫外光刻和各向同性湿蚀刻工艺来实现金半球壳的制造，并通过μ-FTIR 进行表征。测量结果与模拟结果非常吻合。
