Kretschmann based Surface Plasmon Resonance for Sensing in Visible Region

Kretschmann-based surface plasmon resonance (K-SPR) sensing approach using planar thin metal films offer distinct advantages over other label-free sensing techniques in the visible region. SPR phenomenon occurs due to the propagation of electromagnetic waves along the surface of the thin metal layers. Practically, some refractive index changes on the dielectric sample layer will cause changes in surface plasmon polaritons (SPP). The main purpose of using this coupling technique is to match the light-wave vector wave with the SPP vector wave. This paper will give an overview of the design and development of SPR-based sensors utilizing the angular interrogation Kretschmann configuration for detecting the presence of various analytes such as urea, creatinine, glucose, ethanol and uric acid in the visible region. Various sensor layers such as 50-nm thick gold (Au), MoS2/graphene, Au/graphene oxide, Ag/ITO and Au/Ag/ZnO thin films were used to detect the analytes at 633 nm, 670 nm and 785 nm visible electromagnetic wavelengths. Output characteristics such as the reflectivity, full width at half maximum (FWHM), sensitivity, Q factor and Figure of merit (FOM) of the sensors were analyzed. Results of this study was obtained using Lumerical's Finite Difference Time Domain (FDTD) and experimental characterization was obtained using Bionavis SPR equipment; available at IMEN, UKM.