Refractive index sensing with fano resonant L-shaped metasurface

Abstract

Plasmonic Fano resonances are investigated in a coupled metasurface consisting of gold nanobars arranged in L-shaped fashion. The destructive interference between different modes supported by bright and dark nanobars leads to the emergence of sharp asymmetric Fano profile in the extinction spectrum. Multiple Fano resonances in the near-infrared regime are excited by arranging the L-shaped nanostructure in different ways. Furthermore, by increasing the index of refraction of the fill dielectric material around the nanoparticle surface, the Fano resonances exhibit a remarkable red-shift due to which high sensitivity of up to 1360 nm/RIU, figure of merit of 29, and contrast ratio of 66% are realized. These features make the proposed design a promising candidate for efficient bio-chemical sensing.