title: Gradient index metamaterials.
abstract: Metamaterials--artificially structured materials with tailored electromagnetic response--can be designed to have properties difficult or impossible to achieve with traditional materials fabrication methods. Here we present a structured metamaterial, based on conducting split ring resonators (SRRs), which has an effective index of refraction with a constant spatial gradient. We experimentally confirm the gradient by measuring the deflection of a microwave beam by a planar slab of the composite metamaterial over a range of microwave frequencies. The gradient index metamaterial may prove an advantageous alternative approach to the development of gradient index lenses and similar optics, especially at higher frequencies. In particular, the gradient index metamaterial we propose may be suited for terahertz applications, where the magnetic resonant response of SRRs has recently been demonstrated.
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA. drsmith@ee.duke.edu
authors.forename: D R
authors.initials: DR
authors.lastname: Smith
authors.forename: J J
authors.initials: JJ
authors.lastname: Mock
authors.forename: A F
authors.initials: AF
authors.lastname: Starr
authors.forename: D
authors.initials: D
authors.lastname: Schurig