title: Experimental demonstration of electromagnetic tunneling through an epsilon-near-zero metamaterial at microwave frequencies.
abstract: Silveirinha and Engheta have recently proposed that electromagnetic waves can tunnel through a material with an electric permittivity (epsilon) near zero (ENZ). An ENZ material of arbitrary geometry can thus serve as a perfect coupler between incoming and outgoing waveguides with identical cross-sectional area, so long as one dimension of the ENZ is electrically small. In this Letter we present an experimental demonstration of microwave tunneling between two planar waveguides separated by a thin ENZ channel. The ENZ channel consists of a planar waveguide in which complementary split ring resonators are patterned on the lower surface. A tunneling passband is found in transmission measurements, while a two-dimensional spatial map of the electric field distribution reveals a uniform phase variation across the channel--both measurements in agreement with theory and numerical simulations.
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Ruopeng
authors.initials: R
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Cheng
authors.forename: Thomas
authors.initials: T
authors.lastname: Hand
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Mock
authors.forename: Tie Jun
authors.initials: TJ
authors.lastname: Cui
authors.forename: Steven A
authors.initials: SA
authors.lastname: Cummer
authors.forename: David R
authors.initials: DR
authors.lastname: Smith