Antisymmetric toroidal plasmonic metasurfaces

Abstract

In this work, we propose a plasmonic metasurfaces, whose unit cell consisted of a pair of physically connected asymmetric split-ring resonators. Antisymmetric toroidal dipole array is excited. Moreover, toroidal dipoles and hybrid pseudo-anapole states are excited due to the imperfect and perfect destructive interference, respectively. By adjusting the relative position between two toroidal dipoles of the metasurfaces, the imperfect destructive interference was further modified. In addition, this work studied the sensing performance of the metasurface. The displacement sensitivity is around 0.13GHz/mm over the range of 0-8mm. The sensitivity to the refractive index reached up to 3.125GHz/RIU over the range of 1-2. The proposed plasmonic metasurfaces can be the foundation for developing highly sensitivity sensors, frequency-selective surface, active modulation, filter and many other areas.