A new highly sensitive refractive index sensor using vertically coupled plasmonic elliptic-disk up elliptic-ring nanostructure

In this research work, a novel highly sensitive refractive index sensor using elliptical gold and silver nanoparticles are proposed. The main idea of this work is the use of an elliptic-shaped nanoparticle that is decomposed into two particles as a form of elliptic-disk up elliptic-ring to improve the sensitivity. The better optical sensing properties of the proposed nanostructure are the main pion before looking at their details. The optimum arrangement is found to have strong vertical coupling, and hence a high sensitivity. A plasmonic resonance peak is take placed for elliptic nanoparticles. The sensitivity of 440 nm/RIU and full width at half maximum (FWHM) of 55.3 are obtained for that. It is important to mention that these values are 320 nm/RIU and 66.5 for elliptic shape nanoparticles, respectively. By decomposing the elliptic nanoparticles as a form of elliptic-disk up elliptic-ring, the sensitivity is increased to higher than 440nm/RIU. The arrangement of decomposed nanoparticles causes the field to be remarkably enhanced at their point of coupling.