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.
|Number of pages||7|
|State||Published - Apr 10 2019|
Bibliographical noteFunding Information:
Funding. Japan Society for the Promotion of Science (JSPS) (18K04970); Precursory Research for Embryonic Science and Technology (PRESTO) (JPMJPR18I5); Support Center for Advanced Telecommunications Technology Research Foundation (SCAT); Japan Association for Chemical Innovation (JACI); The Precise Measurement Technology Promotion Foundation; TEPCO Memorial Foundation; TUAT president’s discretionary funding.
© 2019 Optical Society of America.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Engineering (miscellaneous)
- Electrical and Electronic Engineering