High sensitivity sensing by all-dielectric metasurface via dual bound states in the continuum

Abstract

In recent years, bound states in the the continuum (BIC) on optical metasurfaces have received a lot of attention due to their unique properties. In this paper, an all-dielectric metasurface based on dual symmetry-protected BIC is proposed. By adjusting the in-plane symmetry of the structure by the size of the circular etch hole, dual quasi-BIC with high Qfactor can be generated, and the modes are analyzed by multipole expansion and near-field electromagnetic distribution. To further change the degree of asymmetry, dual quasi-BIC modes can be shifted and Q-factor adjusted. Finally, due to its potential for high sensitivity and flexible manipulation, this all-dielectric metasurface is well suited for Label free refractive index biosensing, enabling compact sensing devices for a wide range of applications.