Inducing multiple Fano resonant modes in split concentric nanoring resonator dimers for ultraprecise sensing

We report on finite-difference time domain analysis of silicon split concentric ring resonator dimers (SCRRDs) with nanoscale dimensions deposited on a dielectric substrate to design all-dielectric polarization-dependent metamaterial (MM) structures. Investigating the optical response of an SCRRD on a quartz (SiO₂) substrate, we verified that it can be considered as a meta-atom to design a MM. The proposed structure is able to support double sharp Fano resonances in the visible spectrum under transverse electric polarization excitation. Immersing the all-dielectric MM in various chemical liquids with different refractive indices and calculating the transmission spectra, we estimated the sensitivity of the presented MM as 497 nm/RIU and the corresponding figure of merit as 118.5. This study could help designing ultra-sensitive, low-cost and efficient bio-chemical sensors based on all-dielectric components. (paper)