Frontiers in Physics (Jul 2020)

Double Fano Resonances in S-Shaped Plasmonic Metasurfaces in Terahertz Region

  • Weihang Xu,
  • Lingling Chen,
  • Fangming Zhu,
  • Jianjun Liu,
  • Chuanshuai Sui,
  • Zhi Hong

DOI
https://doi.org/10.3389/fphy.2020.00256
Journal volume & issue
Vol. 8

Abstract

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We numerically and experimentally demonstrated double Fano resonances in a simple S-shaped plasmonic metasurface in the terahertz frequency range. Apart from the electric-LC resonance and electric dipole (ED) resonance, two trapped modes are excited in two different types of asymmetric S-shaped structures in the frequency range 0.2–1.4 THz, which are mainly attributed to a magnetic dipole (MD) and an electric quadrupole (EQ). Thereafter, double Fano resonances [one Fano and one electromagnetically induced transparency (EIT) resonance] are achieved via the coupling of the two dark trapped modes and a broad bright ED at normal incidence of the metasurfaces. Furthermore, under oblique incidence, strong Fano responses can be observed; they are considerably enhanced in asymmetric structures, and even in a symmetric structure. The proposed S-shaped plasmonic metasurfaces are easy to fabricate and have potential applications in multi-wavelength optical switches, filters, and sensors.

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