A guided-wave surface plasmon resonance based sensor using graphene layer for detect the biomolecules has been analyzed. The use of waveguide layer between the gold film and graphene significantly improves the penetration depth and increases the sensitivity, then graphene layer is used to enhance the adsorption of the biomolecules. The thickness and materials of waveguide layer along with the number of graphene layer have been optimized to achieve the best performance of the sensor in terms of sensitivity. The highest sensitivity with 228.8°/RIU is obtained for visible wavelength with optimized thickness of gold and waveguide layer as 45nm and 10nm respectively while the materials of waveguide layer is chosen as zinc oxide and the optimum number of graphene layers is 2.We believe that this sensor could find potential applications in biological detection.
In order to explore the key factors of the SPR effect, such as sensitive material, thickness of sensitive metal film, incident angle and wavelength, especially the affection of the incident light wavelength on the modulated reflectivity, calculations and analyses are carried out in this paper. Simulation results show that Ag has the lowest reflectivity when the incident light with shorter wavelength in visible wave band, Au has the lowest reflectivity with red light, and Cu has the best effect from 600 nm to infrared band. The ranges of thickness measurement for thin films can be obtained when the light source wavelength and incidence angle are fixed with the adopted metal sensitive material. Moreover, there is a special range of incidence angle that can put up a significant SPR effect phenomenon when there are definite metal films and wavelength of incident light.