title: Broadband gradient index microwave quasi-optical elements based on non-resonant metamaterials.
abstract: Utilizing non-resonant metamaterial elements, we demonstrate that complex gradient index optics can be constructed exhibiting low material losses and large frequency bandwidth. Although the range of structures is limited to those having only electric response, with an electric permittivity always equal to or greater than unity, there are still numerous metamaterial design possibilities enabled by leveraging the non-resonant elements. For example, a gradient, impedance matching layer can be added that drastically reduces the return loss of the optical elements due to reflection. In microwave experiments, we demonstrate the broadband design concepts with a gradient index lens and a beam-steering element, both of which are confirmed to operate over the entire X-band (roughly 8-12 GHz) frequency spectrum.
authors.affiliation: Center for Metamaterials and Integrated Plasmonics and Department of Electrical and Computer Engineering, Duke University, Box 90291, Durham, NC 27708, USA.
authors.forename: Ruopeng
authors.initials: R
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Cheng
authors.forename: Jessie Y
authors.initials: JY
authors.lastname: Chin
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Mock
authors.forename: Tie Jun
authors.initials: TJ
authors.lastname: Cui
authors.forename: David R
authors.initials: DR
authors.lastname: Smith
mesh_terms: D004563:Electrochemistry; D055590:Electromagnetic Phenomena; D004867:Equipment Design; D008420:Manufactured Materials; D008422:Materials Testing; D008872:Microwaves; D015233:Models, Statistical; D055095:Optics and Photonics; D010825:Physics / Q000379:methods; D012031:Refractometry; D012542:Scattering, Radiation