title: Terahertz Artificial Dielectric Lens.
abstract: We have designed, fabricated, and experimentally characterized a lens for the THz regime based on artificial dielectrics. These are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. For example, the well-known dielectric property, the refractive index, which usually has a value greater than unity, can have a value less than unity in an artificial dielectric. For our lens, the artificial-dielectric medium is made up of a parallel stack of 100 μm thick metal plates that form an array of parallel-plate waveguides. The convergent lens has a plano-concave geometry, in contrast to conventional dielectric lenses. Our results demonstrate that this lens is capable of focusing a 2 cm diameter beam to a spot size of 4 mm, at the design frequency of 0.17 THz. The results further demonstrate that the overall power transmission of the lens can be better than certain conventional dielectric lenses commonly used in the THz regime. Intriguingly, we also observe that under certain conditions, the lens boundary demarcated by the discontinuous plate edges actually resembles a smooth continuous surface. These results highlight the importance of this artificial-dielectric technology for the development of future THz-wave devices.
authors.affiliation: Brown University, School of Engineering, Providence, RI 02912, USA.
authors.forename: Rajind
authors.initials: R
authors.lastname: Mendis
authors.affiliation: Osaka University, Graduate School of Engineering Science, Toyonaka Osaka 560-8531, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Nagai
authors.affiliation: Rice University, Department of Electrical and Computer Engineering, Houston, TX 77005, USA.
authors.forename: Yiqiu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Brown University, School of Engineering, Providence, RI 02912, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Karl
authors.affiliation: Brown University, School of Engineering, Providence, RI 02912, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Mittleman