A Bifunctional Silicon Dielectric Metasurface Based on Quasi-Bound States in the Continuum

Abstract

Quasi-bound states in the continuum provide an effective and observable way to improve metasurface performance, usually with an ultra-high-quality factor. Dielectric metasurfaces dependent on Mie resonances have the characteristic of significantly low loss, and the polarization can be affected by the parameter tuning of the structure. Based on the theory of quasi-bound states in the continuum, we propose and simulate a bifunctional resonant metasurface, whose periodic unit structure consists of four antiparallel and symmetrical amorphous silicon columns embedded in a poly(methyl methacrylate) layer. The metasurface can exhibit an extreme Huygens’ regime in the case of an incident plane wave with linear polarization, while exhibiting chirality in the case of incident circular polarized light. Our structure provides ideas for promoting the multifunctional development of flat optical devices, as well as presenting potential in polarization-dependent fields.

Readiness Assessment of Public University in Bangladesh for Education 4.0: A Case Study of Shahjalal University of Science and Technology – Sylhet, Bangladesh

“…The crossings area confirms that the coupling coefficient, k is zero, proving that both resonances are orthogonal. It is consistent with the concept of an extreme Huygens' metasurface because the transmittance approaches unity with a large quality factor, Q in the crossing location [46,52,61]. However, when the superstate is replaced by a refractive index, n = 1.42 material, the vertical symmetry between the silica substrate and the superstate is broken.…”

“…To support symmetry-protected BIC, we proposed a periodic asymmetric dome-shaped alldielectric metasurface with in-plane symmetry. In comparison to other materials, silicon structures are considerably more advantageous due to their high transmission rate [50,51], minimal losses [52,53], and well-established fabrication method [54,55]. Silica, on the other hand, functions as the substrate for this structure because of its transparency in the visible and infrared range enabling efficient light transmission.…”