Experimental demonstration of a silicon-slot quasi-bound state in the continuum in near-infrared all-dielectric metasurfaces. (June 2023)

• Record Type: Journal Article
• Authors: Algorri, J.F.; Dell'Olio, F.; Ding, Y.; Labbé, F.; Dmitriev, V.; López-Higuera, J.M.; Sánchez-Pena, J.M.; Andreani, L.C.; Galli, M.; Zografopoulos, D.C.
• Is Part Of: Optics & laser technology. Volume 161(2023)
• Publication Date: 2023-06
• Subjects: Metamaterials -- Biosensing -- Bound states in the continuum -- Nanofabrication -- Silicon metasurfaces -- Symmetry-protected modes; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2023.109199
• Languages: English
• ISSNs: 0030-3992

Abstract

Abstract: We theoretically and experimentally investigate a metasurface supporting a silicon-slot quasi-bound state in the continuum (qBIC) mode resonating in the near-infrared spectrum. The metasurface is composed of circular slots etched in a silicon layer on a sapphire substrate. The symmetry of the metasurface unit cell is reduced in order to provide access to the symmetry-protected mode, whose properties are investigated by finite-element full-wave and eigenfrequency analysis. The measured transmittance spectra verify the excitation of the investigated qBIC mode with experimental quality factors exceeding 700. The near-field distribution of the resonant qBIC mode shows strong field confinement in the slots, leading to high sensitivity values for refractometry. Graphical abstract: Highlights: A symmetry-protected bound state in the continuum is studied in a silicon metasurface. The resonant mode shows very strong field enhancement in slotted regions. Refractometric sensitivity above 400 nm/RIU thanks to strong light-matter interaction. The measured resonant wavelengths confirm the symmetry-protected nature of the mode. Quality factors higher than 700 are experimentally demonstrated.