Polarization sensitive toroidal dipole metasurface for switch and magnetic field tunability

Abstract

We design and numerically investigate an all-dielectric metasurface, a combination of rectangular bar and two nanoring resonators, that exhibits strong toroidal response with high polarization sensitivity and large modulation depth. With coupled-resonator effects, Fano resonance with toroidal response can be switched on and off at orthogonal orientations. Moreover, directional toroidal dipole can be achieved and controlled by symmetry breaking of metasurface, which can effectively tailor the local magnetic field with high Q-factor and strong field enhancements simultaneously, while keeps strong toroidal dipole responses. We envision that strong toroidal response in proposed metasurface has potential applications in designing switching and modulators.