Open AccessEpsilon-near-zero three-dimensional metamaterial for manipulation of terahertz beams
Author(s) -
Takao Suzuki,
Tatsuya Sato,
Mitsuaki Sekiya,
John C. Young
Publication year - 2019
Publication title -
applied optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 197
eISSN - 2155-3165
pISSN - 1559-128X
DOI - 10.1364/ao.58.003029
Subject(s) - terahertz radiation , optics , metamaterial , microlens , lens (geology) , refractive index , transformation optics , superlens , physics , materials science , terahertz spectroscopy and technology
Metamaterials offer the potential of unprecedented refractive indices and evolution into metadevices for the manipulation of electromagnetic waves. However, the potential of the epsilon-near-zero (ENZ) concept has not been fully demonstrated in the terahertz waveband. Most conventional ENZ lenses have a uniform distribution of refractive indices in spite of their three-dimensional structure. Here, inspired by the ENZ concept, we demonstrate the two-dimensional distribution of a three-dimensional ENZ lens realized by circular openings of varying diameters on metal plates and apply it to a metal-slit array lens with gradient indices of 0<n eff <1. The measurements of a fabricated metal-slit array lens with circular openings observe the focusing effect of a terahertz wave. We also apply the ENZ concept to the design of microlens arrays. The control of the gradient of the ENZ potentially offers a wide range of applications.