All-Dielectric Silicon Metasurface with Strong Subterahertz Toroidal Dipole Resonance

A single-layer, all-dielectric metasurface exhibiting a strong toroidal resonance in the low-atmospheric loss radio window of the subterahertz W-band is theoretically proposed and experimentally demonstrated. The metasurface is fabricated on a high-resistivity floating-zone silicon wafer by means of a single-process, wet anisotropic etching technique. The properties of the toroidal mode of both the constituent dielectric elements and the metasurface are rigorously investigated by means of the multipole decomposition technique and full-wave simulations. The experimental demonstration of such a compact, all-silicon metasurface opens new venues of research in the investigation of toroidal modes and the engineering of functional millimeter-wave components, which can be scaled to terahertz and higher frequencies of the electromagnetic spectrum.