Supercavity modes in silicon-based metasurfaces

Bound states in the continuum, which exist in realistic samples in a form of high quality (Q) factor supercavity modes, catch a lot of attention due to their promising applications in optics. Here we study silicon metasurfaces supporting a number of supercavity modes. The metasurfaces consist of silicon rods with circular or rectangular profile. We analyze the array of circular rods by exploiting the multiple scattering theory. More practical metasurfaces with rectangular nanoblocks on a silicon substrate are examined using numerical simulations. We obtain Q factor dependences on geometric parameters of the metasurfaces. The rapid Q factor growth typical for supercavity mode is found for the systems under study.