Theoretical design of a surface plasmon resonance sensor with high sensitivity and high resolution based on graphene-WS2 hybrid nanostructures and Au-Ag bimetallic film

We proposed a high sensitivity and a high resolution surface plasmon resonance sensor composed of graphene-WS2 hybrid nanostructure and Au-Ag bimetallic-layers film. The bimetallic-layer configuration uses the high sensitivity of gold and the narrow full width at half maximum (FWHM) of silver to improve the sensor's sensitivity and resolution respectively. Graphene and WS2 serve as an effective light absorption medium. Once they cover the bimetallic-layer, the sensitivity can be further improved significantly. Graphene-WS2-Au-Ag model shows a higher sensitivity and higher resolution than that of the conventional sensing scheme where pure Au thin film is used. In our paper, we mainly use Fresnel equations and the transfer matrix method (TMM) to study the reflectivity and sensitivity as well as the full width at half maximum (FWHM) of the SPR sensor.