Ultrasensitive Refractive Index Sensing Based on Hybrid High-Q Metasurfaces

Abstract

High sensitivity and a large quality factor (Q) are two desirable goals to achieve a high figure of merit (FoM) in refractive index (RI) sensing. However, simultaneously satisfying these two goals is challenging. Herein, we propose a new class of hybrid high-Q metasurfaces, which are dielectric arrays standing on a Au plasmonic nanofilm, possessing the advantages of both high RI sensitivity and a large Q. The hybrid metasurface can support the plasmon-coupled lattice mode, which has extremely narrow full width at half-maximum (fwhm) resulting in a high-Q. The hybrid metasurface can be fabricated by a facile straightforward lithography technique and exhibits ultrahigh FoM values over a wide RI range (1–1.384) due to its narrow fwhm (smaller than 1 nm) and tunable high RI sensitivity. The highest Q and FoM values of 2370 and 1431 were experimentally demonstrated, respectively, giving the proposed hybrid metasurface great potential for building advanced optical biosensors in future applications.