Symmetric and antisymmetric multipole electric-magnetic fano resonances in elliptic disk- nonconcentric split ring plasmonic nanostructures

Abstract

A plasmonic nanostructure composed of a displaced elliptical disk in a nonconcentric split ring is proposed and investigated theoretically by the finite difference time domain method. The simulated scattering spectra and electric field distributions reveal that multiple Fano resonances can be formed due to the destructive interference of the longitudinal dipole mode of the disk and multiple multipole magnetic modes of the split ring. It is also found that the spectral position of each Fano dip is insensitive to the offset caused by moving the disk in either direction, but the depth varies to a different extent. When the disk moves parallel to the split, it is very suitable for the generation and evolution of the symmetric Fano resonance, particularly the structural symmetry of the split ring is further broken. As the disk moves perpendicular and closer to the split, the depth of each antisymmetric Fano resonance increases, while the appeared symmetric ones weaken. Such a nanostructure may be used as a potential platform for spectral line shaping and multiwavelength bio-chemical sensing.