A numerical approach to surface plasmon resonance sensor design with high sensitivity using single and bimetallic film structures

Abstract

Up to now, surface plasmon resonance (SPR) has been widely studied for biological and chemical sensing applications. The present study investigates numerically the optical characteristics for the single Au film and bimetallic Ag-Au film SPR configurations by using the multiple beam interference matrix (MBIM) method. The Kretschmann configuration is used for excitation of surface plasmon wave (SPW) with the use of angular modulation. The estimated results of the reflectance, the phase shift, and the magnetic field intensity enhancement are provided for predicting the optimum metal film thickness which can yield highest sensitivity in measuring the SPR signal. As a result, it is observed that the optimum thickness of a single Au film is 52 nm, whereas for a bimetallic Ag-Au film, the optimum film thickness values are 36 nm for Ag and 5 nm for Au, respectively. Moreover, it is concluded that the phase shift would be remarkably appropriate in detecting the SPR sensor signal because of the high sensitivity it offers compared to other values, such as the full width half maximum (FWHM) of reflectance and the enhancement of magnetic field intensity.