A dielectric metasurface supporting a variety of quasi-bound states in the continuum (qBICs), including the intricate dark toroidal dipole and toroidal quadrupole Mie modes, is theoretically and experimentally investigated in the near-infrared. The metasurface consists of square slots etched into a thin silicon layer and periodically arrayed in a subdiffractive lattice residing on a sapphire substrate. The modal properties of the qBICs, i.e., the quality factors alongside the near- and far-field characteristics…
