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Surface plasmons supported by various metallic nanostructures have given rise to several significant breakthroughs in the field of integrated photonic devices due to its ability to effectively confine and enhance optical field in subwavelength volume. In particular, the demand to actively control optical responses of plasmonic systems becomes urgent for the miniaturization of signal processing devices, surface-enhanced Raman scattering (SERS) substrates and biochemical sensors. In this paper, we systematically investigate the plasmon modes as well as their interaction in a layered nanostructure composed of a periodically-arranged radiative nanoring and a metallic ground plane, as well as a thin insulating spacer. A tunable transparent peak on the background of the broadband plasmon resonance emerges in the reflection spectrum as changing the periodicity of nanoparticle array, a plasmonic analogue of electromagnetically induced transparency (EIT). Owing to the structural symmetry of the rings, we demonstrate a new scheme of controlling the interference between localized and delocalized plasmons by means of incident polarization and believe that the proposed metasurface may find applications in optical switching if the polarization-controlled components are introduced. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate that an electromagnetically induced transparency (EIT)-like behavior is induced by the coupling of two magnetic resonances in a planar terahertz (THz) metamaterial structure, which consists of a U-shaped split ring (USR) as one bright resonator and a cut wire pair (CWP) as one dark resonator. It is found that the EIT-like spectral response is insensitive to the lateral distance between the two magnetic resonators, whereas an on-to-off modulation of the amplitude of the transparency window can be achieved by moving the USR vertically along the CWP. The underlying physical mechanism is mainly attributed to magneto-inductive excitation of the CWP. This investigation may provide an insight of the role of magnetic coupling in achieving EIT-like effect, inspiring interest in the developments of magnetically tunable transparency metamaterial for a wide range of optical devices with switching and modulation capabilities. [ABSTRACT FROM AUTHOR]

In this paper, a plasmonic analogue of electromagnetically induced transparency (EIT) is demonstrated theoretically in a T-shaped silver nanohole array. A sharply narrow reflectance transparency window is clearly observed within the background spectrum of the broad dipole-like resonance at optical frequencies when structural asymmetry is introduced. Furthermore, the transparency peak exhibits highly sensitive response to the refractive index of surrounding medium and yield a sensitivity of 725 nm/refractive index unit (RIU), which ensures our proposed nanohole array as an excellent plasmonic sensor. In addition, the dependence of figure of merit (FOM) on structural asymmetry is investigated numerically to optimize the sensing performance of the EIT-based sensor. [ABSTRACT FROM AUTHOR]