Fuchs Sondheimer-Drude Lorentz model and Drude model in the study of SPR based optical sensors: A theoretical study

A comparative study on the sensing performance of gold coated surface plasmon resonance (SPR) based sensors has been presented wherein the dispersive nature of the gold has been accounted for by Fuchs Sondheimer-Drude Lorentz (FS-DL) and Drude models. SPR transmittance spectra have been studied with varying specularity coefficients. Further, a detailed study of detection accuracy and sensitivity with both Drude model and FS-DL model has been carried out for varying gold layer thickness, sensing medium refractive indices and with three different values of specularity coefficient for fiber-coupled sensors. Furthermore, using FS-DL model, SPR insensitive thickness of the metal layer is determined for both fiber- coupled and prism-coupled sensing probes.