Quasi-bound states in the continuum with robust resonance wavelength in an all-dielectric planar metasurface

Abstract Bound states in the continuum (BICs) supported by metasurfaces broaden the possibilities for enhancing light-matter interaction. Yet the shift of resonance wavelength towards asymmetric perturbation and polarization state variation affects its practical application. In the present study, we design a metasurface to achieve quasi-BICs with both asymmetry and polarization independence through in-plane perturbation with geometry compensation and rotational symmetry. Through multipole decomposition, we reveal the internal physical mechanism from which the dual-band BIC modes are originated; magnetic dipole and toroidal dipole, respectively. Furthermore, based on the designed metasurface, a promising application as an environmental sensor is discussed. The present study provides potential scenarios for the manipulation of BICs with higher robustness and better performance.