Open AccessStrongly resonant silicon slot metasurfaces with symmetry-protected bound states in the continuum
Author(s) -
José Francisco Algorri,
Francesco Dell’Olio,
Pablo Roldán-Varona,
Luis Rodŕıguez-Cobo,
José Miguel LópezHiguera,
José Manuel SánchezPena,
Dimitrios C. Zografopoulos
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.415377
Subject(s) - multipole expansion , fano resonance , optics , resonator , physics , q factor , transmittance , metamaterial , silicon , wavelength , dielectric , resonance (particle physics) , optoelectronics , atomic physics , plasmon , quantum mechanics
In this work, a novel all-dielectric metasurface made of arrayed circular slots etched in a silicon layer is proposed and theoretically investigated. The structure is designed to support both Mie-type multipolar resonances and symmetry-protected bound states in the continuum (BIC). Specifically, the metasurface consists of interrupted circular slots, following the paradigm of complementary split-ring resonators. This configuration allows both silicon-on-glass and free-standing metasurfaces and the arc length of the split-rings provides an extra tuning parameter. The nature of both BIC and non-BIC resonances supported by the metasurface is investigated by employing the Cartesian multipole decomposition technique. Thanks to the non-radiating nature of the quasi-BIC resonance, extremely high Q-factor responses are calculated, both by fitting the simulated transmittance spectra to an extended Fano model and by an eigenfrequency analysis. Furthermore, the effect of optical losses in silicon on quenching the achievable Q-factor values is discussed. The metasurface features a simple bulk geometry and sub-wavelength dimensions. This novel device, its high Q-factors, and strong energy confinement open new avenues of research on light-matter interactions in view of new applications in non-linear devices, biological sensors, and optical communications.