Design of localized surface plasmon resonance-based refractive index sensor using optical fiber

The paper proposes a design of a localized surface plasmon resonance-based refractive index sensor for the detection of a chemical compound availing unclad geometry of the optical fiber. The geometry is explored to analyze the sensing behavior and coupling phenomenon at the metal-dielectric interface. The finite element method (FEM) is applied numerically to evaluate the analytical change in the reflectance spectra of the fiber model by inoculating potassium nitrate compound. The resonance shift and reflectance of the surface plasmon resonance (SPR) signal obtained after the optimization of structural parameters enhance the sensing performance of the prototype. The sensor exhibits a maximum sensitivity of 80.2919 rad/RIU for a 1.56 high refractive index analyte and minimum sensitivity of 2.3446 rad/RIU for a 1.33 low refractive index analyte. The proposed sensor is modelled in such a way that it can be employed in various sensing applications for a wide range of refractive indices.