Advanced refractive index sensor using 3-dimensional metamaterial based nanoantenna array

Photonic researchers have increasingly exploiting nanotechnology. Due to the advent of numerous prevalent nanosized manufacturing methods that enable adequate shaped nanostructures to be manufactured and investigated as a method of exploiting nano-structured. Owing of the variety of optical modes, hybrid nanostructures that integrate dielectric resonators with plasmonic nanostructures also offer enormous potentials. In this work, we have explored a hybrid coupled nano-structured antenna with stacked lithium tantalate (LiTaO₃)/Aluminium oxide (Al₂O₃) multilayer operating at infrared ranging from 400 nm-2000 nm. Here, the sensitivity response has been explored of the hybrid nano-structured array made up of the gold metal elliptical disk placed on the top of a quartz substrate and excite the different modes in both materials. It shows large electromagnetic confinement at the separation distance (d) of the dimers due to strong surface plasmon resonance (SPR). The influence of the structural dimensions is investigated to optimise the sensitivity of stacked elliptical dimers. The designed hybrid coupled nano-structure with the combination of gold (Au) and Lithium tantalate (LiTaO₃) /Aluminium oxide (Al₂O₃) with h₁ = h₂ = 10 nm each 10 layer exhibits bulk sensitivity (S), which is the spectrum shift unit per refractive index (RI) change in the surrounding medium was calculated to be 730 and 660 nm/RIU with major axis, (a) = 100 nm, minor axis, (b) = 10 nm, separation distance (d) = 10 nm, height, (h) = 100 nm (with or without stacked). The outcomes from the proposed hybrid nanostructure have been compared with a single metallic (only gold) elliptical paired nano-structure to show a significant improvement in the sensitivity using hybrid nano-structure. Depending on these findings, we demonstrated a roughly two-fold increase in sensitivity (S) by utilising a hybrid nano linked nano-structure with respect to identical nano structure, which competes with traditional sensors with the same height, (h) based on localised surface plasmon resonances. Our innovative plasmonic hybrid nanostructures provide a framework for developing plasmonic nanostructures for use in various sensing applications.