Polarization independent and tunable plasmonic structure for mimicking electromagnetically induced transparency in the reflectance spectrum

This paper proposes a plasmonic metamaterial that is able to mimic electromagnetically induced transparency in the reflectance spectrum within the GHz frequency range. Each meta-atom consists of a cross-slot structure as the bright resonator positioned on one side of the FR-4 substrate, and four spiral structures as the dark resonator located on the opposite side. Free space experimental results demonstrate that at normal incidence of plane wave, the metamaterial possesses the properties of tunability and polarization independence. In addition, based on simulation results the metamaterial also possesses slow wave property, with group refractive index of 56; and refractive-index-based sensing capability, with figure of merit of 6.1. In the strong coupling configuration, the plasma frequency and coupling constant of the metamaterial were calculated to be approximately 5.4 × 1010 rad s−1 and 9.8 × 109 rad s−1 respectively. While the respective damping constants of the bright resonator and dark resonator were calculated to be approximately 4.6 × 1010 rad s−1 and 1.9 × 1010 rad s−1.