Multi-Band Circular Dichroism Induced by Surface Plasmonic Resonance in Bi-Layer Semi-Ring/Rod Nanostructure

Plasmonic chiroptical effects have received more and more attention for their wide application in the fields of plasmonic sensing, biological detection, and analytical chemistry. In this study, we propose a bi-layer semi-ring/rod nanostructure array. The results calculated by the finite element method show that under the exciting of left-handed circularly polarized light and right-handed circularly polarized light, the nanostructure can produce strong multi-band circular dichroism (CD) signal due to the different coupling modes of electric dipole-electric dipole or magnetic dipole-electric dipole. In addition, the CD signal is strongly dependent on the tilt angle theta, the length L of nanorod, the radius R-2, and the distance D. In particular, the adjustment of theta can realize the switching of the CD signal between appear and vanish, and the change of L can achieve manipulation only for a particular resonance mode. The results in this study show that the bi-layer semi-ring/rod array nanostructure provides guidance for the generation of CD using plasmonic nanostructures, and it also shows potential application in spectral anti-crosstalk.