Open AccessTerahertz metasurfaces with a high refractive index enhanced by the strong nearest neighbor coupling
Author(s) -
Siyu Tan,
Fengping Yan,
Leena Singh,
Wei Cao,
Ningning Xu,
Xiang Hu,
Ranjan Singh,
Mingwei Wang,
Weili Zhang
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.029222
Subject(s) - refractive index , terahertz radiation , optics , metamaterial , coupling (piping) , physics , resonator , materials science , optoelectronics , metallurgy
The realization of high refractive index is of significant interest in optical imaging with enhanced resolution. Strongly coupled subwavelength resonators were proposed and demonstrated at both optical and terahertz frequencies to enhance the refractive index due to large induced dipole moment in meta-atoms. Here, we report an alternative design for flexible free-standing terahertz metasurface in the strong coupling regime where we experimentally achieve a peak refractive index value of 14.36. We also investigate the impact of the nearest neighbor coupling in the form of frequency tuning and enhancement of the peak refractive index. We provide an analytical circuit model to explain the impact of geometrical parameters and coupling on the effective refractive index of the metasurface. The proposed meta-atom structure enables tailoring of the peak refractive index based on nearest neighbor coupling and this property offers tremendous design flexibility for transformation optics and other index-gradient devices at terahertz frequencies.