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Refractive index sensing by all-dielectric metasurfaces supporting quasi-bound states in the continuum

Abstract: All-dielectric metasurfaces have attracted increasing attention due to their negligible losses and sharper resonances compared to their metallic counterparts. In this work, we numerically studied the optical performance of a novel alldielectric metasurface based on complementary split-ring resonators (CSRRs), in which ultrathin slots were periodically etched in a thin silicon layer. The proposed CSRR metasurface exhibits two multipolar resonances in the near-infrared (NIR) window. Moreover, a quasi-bound state in the continuum (quasi-BIC) with an ultra-high quality factor can be excited by breaking the symmetry of the structure. Taking advantage of the high-quality factor quasi-BIC mode and its sensitivity to the superstrate medium refractive index (S = [Di] res/[Dn]), we design an ultra-high figure of merit (FoM = S/FWHM) refractive index sensor for biomedical applications. By three-dimensional finite element method (3D-FEM), we evaluate the sensitivity of the sensing device to the variation of the superstrate refractive index in the range 1.31-1.33, which is typical for aqueous solutions. Our simulations reveal that a sensitivity of S ~ 155 nm RIU-1 and an extraordinary FoM ~ 387500 RIU-1 can be achieved using the ultra-narrow quasi-BIC resonance in the CSRR metasurface structure. The proposed approach opens new paths to develop flat biochemical sensors with high accuracy and real-time performance.

Other conference communications or articles related to authors from the University of Cantabria

 Authorship: Samadi M., Abshari F., Algorri J.F., Roldán-Varona P., Rodríguez-Cobo L., López-Higuera J.M., Sánchez-Pena J.M., Zografopoulos D.C., Dell'olio F.,

 Congress: Laser Resonators, Microresonators, and Beam Control (24ª : 2022 : San Francisco, California)

 Publisher: SPIE Society of Photo-Optical Instrumentation Engineers

 Publication date: 04/03/2022

 No. of pages: 6

 Publication type: Conference object

 DOI: 10.1117/12.2608256

 ISSN: 0277-786X,1996-756X

 Publication Url: https://doi.org/10.1117/12.2608256

Authorship

SAMADI, MOHSEN

ABSHARI, FATEMEH

PABLO ROLDAN VARONA

LUIS RODRIGUEZ COBO

JOSE MANUEL SANCHEZ PENA

ZOGRAFOPOULOS, DIMITRIOS C.

FRANCESCO DELL´OLIO