Polarization-independent bound state in the continuum without the help of rotational symmetry

Recently, research about bound states in the continuum (BICs) has become more and more attractive. Nanostructures with rotational symmetry are usually utilized to realize polarization-independent quasi-BIC resonances. Here, we propose a new, to the best of our knowledge, scheme for a polarization-independent quasi-BIC without the help of rotational symmetry. With the rotation of the polarization direction of the incident light, a quasiBIC resonance can be consistently observed in a dielectric cubic tetramer metasurface without rotational symmetry. Based on far-field multipolar decomposition and near-field electromagnetic distributions, it is found that different multipoles exhibit different dependences on the polarization direction, and the switch between electric and magnetic quadrupoles results in polarization-independent quasi-BIC resonance. Our findings provide an alternative scheme to design polarization-independent devices and promote wider potential applications.(c) 2023 Optica Publishing Group

Automated summary

Research on bound states in the continuum (BICs) has gained increasing attention recently. This study proposes a new scheme for polarization-independent quasi-BIC without rotational symmetry, achieved through the rotation of the incident light's polarization direction. By investigating far-field multipolar decomposition and near-field electromagnetic distributions, it is demonstrated that the switch between electric and magnetic quadrupoles leads to the observed polarization-independent quasi-BIC resonance. This finding offers an alternative approach for designing polarization-independent devices and expanding their potential applications.