Highly sensitive surface plasmon-based refractive index sensor in the optical communication band using ZnS-PVP layers

Abstract

Amongst the prominent plasmonic metals, Aluminum (A1) has become a popular alternative for its low cost, broader spectral coverage, and narrow linewidth of the resonance curves. This paper proposes a highly sensitive Al-ZnS-PVP-based plasmonic device for sensing analysis in the spectral regime comprising near-infrared band. This SPR-based plasmonic device is designed with a thin Al-coated glass prism, followed by Zinc Sulfide (ZnS), and PolyVinylPyrrolidone (PVP) overlayers in sequence. ZnS and PVP are employed as high-index dielectric layers and polymers for increasing the analyte interaction. At 1550 nm, the optical output is observed over a range of incident angles, after following a series of optimizations for Al thin film along with PVP and ZnS thicknesses. These are undertaken for maximum performance parameters, i.e., Figure of Merit (FOM) including sensitivity. The proposed plasmonic configuration offers a sensitivity of 121°/RIU with 374.6 RI$\mathrm{U}^{-1}$ as the FOM. Overall, the proposed sensor reported higher sensing parameters compared to other plasmonic devices based on 2D nanomaterials. The suggested sensor will be valuable for detecting chemical and biological samples from an experimental standpoint for the optical communication window.