Metamaterial inspired terahertz devices: from ultra-sensitive sensing to near field manipulation

Abstract

We present a review of terahertz plasmonic metamaterial devices that have functionalities and applications ranging from sensing, enhanced electromagnetic fields, and near field manipulation. Metamaterials allow the properties of light propagation to be manipulated at will by using a combination of appropriately designed geometry and suitable materials at the unit cell level. In this review, we first discuss the sensing aspect of a planar plasmonic metamaterial and how to overcome its limitations. Conventional symmetric metamaterials are limited by their low Q factor, thus we probed the symmetry broken plasmonic metamaterial structures in which the interference between a broad continuum mode and a narrow localized mode leads to the excitation of the sharp Fano resonances. We also discuss the near field mediated excitation of dark plasmonic modes in metamaterials that is caused by a strong coupling from the bright mode resonator. The near field coupling between the dark and bright mode resonances leads to classical analogue of electromagnetically induced transparency in plasmonic systems. Finally, we discuss active switching in terahertz metamaterials based on high temperature superconductors that holds the promise of reducing the resistive losses in these systems, though it fails to suppress the radiation loss in plasmonic metamaterial at terahertz frequencies.