Title
Antimatched Electromagnetic Metasurfaces for Broadband Arbitrary Phase Manipulation in Reflection
Publication Date
1-3-2018
Department
Ames Laboratory; Physics and Astronomy
Campus Units
Physics and Astronomy, Ames Laboratory
Report Number
IS-J 9616
DOI
10.1021/acsphotonics.7b01415
Journal Title
ACS Photonics
Volume Number
5
Issue Number
3
First Page
1101
Last Page
1107
Abstract
Metasurfaces impart phase discontinuities on impinging electromagnetic waves that are typically limited to 0–2π. Here, we demonstrate that multiresonant metasurfaces can break free from this limitation and supply arbitrarily large, tunable time delays over ultrawide bandwidths. As such, ultrathin metasurfaces can act as the equivalent of thick bulk structures by emulating the multiple geometric resonances of three-dimensional systems that originate from phase accumulation with effective material resonances implemented on the surface itself via suitable subwavelength meta-atoms. We describe a constructive procedure for defining the required sheet admittivities of such metasurfaces. Importantly, the proposed approach provides an exactly linear phase response so that broadband pulses can experience the desired group delay without any distortion of the pulse shape. We focus on operation in reflection by exploiting an antimatching condition, satisfied by interleaved electric and magnetic Lorentzian resonances in the surface admittivities, which completely zeroes out transmission through the metasurface. As a result, the proposed metasurfaces can perfectly reflect a broadband pulse imparting a prescribed group delay. The group delay can be tuned by modifying the implemented resonances, thus opening up diverse possibilities in the temporal applications of metasurfaces.
Language
en
Publisher
Iowa State University Digital Repository, Ames IA (United States)