Ultrathin dual-mode filtering characteristics of terahertz metamaterials with electrically unconnected and connected U-shaped resonators array

摘要

We experimentally and numerically demonstrate dual-mode resonances of electrically unconnected and connected U-shaped resonators array on flexible polyimide substrate in terahertz (THz) region. The unit cell consisting of two back-to-back U-shaped resonators (TUR) shows strong induction-capacitance resonance for TM mode and dipole resonance for TE mode. Then we clarify the transmission spectra characteristics of fourfold U-shaped resonators (FURs), which are composed of two twisted TUR at 90 degrees. Distinct characteristic transmission responses are observed in varied coupled distances, specially, an "L-shaped" resonance is observed at connected FUR which does not exist in unconnected FUR. The polarization tunable property of TUR and polarization-independent characteristics of FUR are adequately clarified. Some applications such as polarization-tunable modulator (peak-to-peak value is about 0.4 for 90 degrees polarization rotation) and polarization-independent dual-channel filter (full width with half maximum (FWHMs) nears to 85 GHz) is proposed and verified experimentally, which may benefit to broaden novel ultrathin flexible THz devices. (C) 2014 Elsevier B.V. All rights reserved.