Polarization-independent Fano metasurface with directional toroidal dipole for magnetic field tunability

Abstract

We have designed and numerically investigated an all-dielectric metasurface consisting of four nanorings located apart with a cross nanobar resonator in between, which supports polarization-independent Fano resonance arising from destructive interference between electric and toroidal dipole moments. Exploiting polarization dependency of toroidal dipole, the polarization of incident light can actively control the direction of toroidal dipole but does not affect Fano resonance. Moreover, our results also manifest that local magnetic field can be dynamically switched on and off based on directional toroidal dipole while maintaining polarization-independent Fano resonance, indicating potential application in efficient switch, light trapping and magnetic hot-spot generation.