Permittivity-asymmetric qBIC metasurfaces for refractive index sensing.

ABSTRACT: Bound states in the continuum (BICs) provide exceptional light confinement due to their inherent decoupling from radiative channels. Small symmetry breaking transforms BIC into quasi-BIC (qBIC) that couples to free-space radiation enabling ultra-high-quality-factor (Q-factor) resonances desirable for refractive index (RI) sensing. In practical implementations, geometric asymmetry is typically employed. However, since the radiative loss remains fixed once fabricated, such metasurfaces exhibit only a horizontal shift of the resonance spectrum in RI sensing, without modification of its overall shape. Here, we demonstrate a permittivity-asymmetric qBIC (ε-qBIC) metasurface, which encodes environmental refractive index variations directly into the asymmetry factor, resulting in an index respons

SUBMITTER: Yang X 

PROVIDER: S-EPMC12717935 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature