Ultrasensitive Refractive Index Sensing Based on the Quasi-Bound States in the Continuum of All-Dielectric Metasurfaces
Journal
Advanced Optical Materials
Date Issued
2022
Author(s)
Abstract
Symmetry-protected quasi-bound states in the continuum (BIC) controlled by metasurfaces with broken in-plane symmetry are widely exploited to achieve highly surface-sensitive and spectrally sharp resonances for nanophotonic biosensors. Through the engineering of silicon-based asymmetric nanobar pairs, a quasi-BIC mode is excited showing a dominant toroidal dipole (TD) and electric quadrupole (EQ) resonant feature in the near-infrared and performs ultrahigh sensitivity in the refractometric monitoring of local environment changes. Contrary to the typical electric and magnetic Mie-type resonances of dielectric resonators with the enhanced field mostly inside the resonator volume, the TD-EQ quasi-BIC mode is found to exhibit strong and tightly confined optical fields at the surface of tilted nanobar pairs, and its refractive-index (RI) sensitivity can be dramatically increased for nanopillars with larger aspect-ratio. The measured (simulated) sensitivity and figure of merit for nanobar pairs with a height of 450 nm reach 608 nm/RIU and 46 (612 nm/RIU and 85), respectively. Such ultrahigh sensitive all-dielectric platform can be fabricated through complementary metal-oxide-semiconductor compatible process and is promising for on-chip integration and sensor miniaturization to a wide range of diagnostic applications. © 2022 Wiley-VCH GmbH.
Subjects
bound states in the continuum; dielectric metasurfaces; electric quadrupole; refractive-index sensing; toroidal dipole
SDGs
Other Subjects
Aspect ratio; CMOS integrated circuits; Dielectric devices; Metals; MOS devices; Oxide semiconductors; Refractive index; Resonators; Bound state in the continuum; Bound-states; Continuum modes; Dielectric metasurface; Electric quadrupoles; Nanobars; Quasibound state; Refractive index sensing; Toroidal dipole; Infrared devices
Type
journal article