Polarization conversion in anisotropic dielectric metasurfaces originating from bound states in the continuum

Abstract

We use the semianalytical Cartesian multipole method to investigate the light transmission and reflection spectra of anisotropic dielectric metasurfaces, and extend the multipole decompositions method to account for cross-polarization conversion effects. We observe sharp high- Q resonances arising from a distortion of symmetry-protected bound states in the continuum in asymmetric dielectric metasurfaces, i.e., quasibound states in the continuum. In addition, by further introducing in-plane symmetric breaking perturbation, the polarization conversions of linearly polarized light can be achieved through quasibound states in the continuum. With the aid of temporal coupled-mode theory, we can obtain the limit of cross-conversion under single high- Q resonance, i.e., 0.25. Our work will help to design dielectric metasurfaces to control the polarization states of light.

Toroidal‐Assisted Generalized Huygens’ Sources for Highly Transmissive Plasmonic Metasurfaces

“…To achieve a highly efficient radiation pattern with minimal backscattered fields, the interference of the multipolar modes of HPMA in the Kerker configuration should be considered. To meet the desire of the circularly polarized optical response and xand y-directions of both the Kerker condition and directivity, the Cartesian multipoles [42][43][44][45] are used for the investigation instead of the spherical ones. We begin by taking the farfield radiation of a plasmonic scatterer into account with consideration of the above-mentioned five leading multipoles (see Table S2, Supporting Information).…”

Tailoring Polarization Conversion in Achiral All-Dielectric Metasurfaces by Using Quasi-Bound States in the Continuum

“…The optical response of BICs has recently been harnessed to achieve polarization conversion [33][34][35][36]. However, one of the main drawbacks of the current approaches is the dependence on the intrinsic chirality of the meta-atoms, or their disposition in chiral arrangements.…”

Kerker Effects and Bound States in the Continuum in PT-Symmetric Dielectric Metasurfaces

“…A true BIC, including symmetry-protected and accidental BICs, is a nonradiating photonic eigenstate of wave equations embedded in the radiation continuum characterized by an infinite value of the Q factor and vanishing resonance width, i.e., they are discrete and spatially bounded, but exist at the same energy as a continuum of states which propagate to infinity. However, the symmetryprotected BIC can transform into quasi-BICs with high but finite Q factors controlled by symmetrybreaking perturbations [9]. What is more, BICinspired resonances are engineered for many important applications, such as polarization conversion [9].…”

“…However, the symmetryprotected BIC can transform into quasi-BICs with high but finite Q factors controlled by symmetrybreaking perturbations [9]. What is more, BICinspired resonances are engineered for many important applications, such as polarization conversion [9].…”