Advances in Grating-Coupled Hybrid Surface Plasmon Resonance at Flat Metal–Analyte Interface

Abstract

In this paper, we theoretically investigate the sensing characteristics of a metallic grating-coupled surface plasmon resonance sensor with the objective of showing their influence on the grating parameters. For comparison, the optical responses of silver (Ag), gold (Au), and copper (Cu), as plasmonic material layers, are separately adopted in the Kretschamann approach. The reflectivity of each plasmonic layer coated on top of a glass prism is analyzed using the wavelength interrogation method. The optical responses of the considered configurations are analyzed, where the impact parameters  are  related  to  the  grating parameters (height, width, and periodicity) and layer thickness that have been suitably optimized. Additionally, the excitation angle of incident light is fixed in the range from 26° to 66°, and the outer medium refractive index is assumed in the range from 1.33 to 1.34. Thus, the obtained results reveal that the proposed structures allow for a  remarkable  coupling  between surface  plasmon  resonance and localized surface plasmon resonance, whose  functionality  as  efficient refractive index sensors  is  characterized by improved wavelength sensitivity in the range λ ≈ 400–100 nm, high figure of merit, and the narrowest spectral full width at half maximum of the resonant plasmonic response. Such preferential limits of the performance parameters should make the suggested multilayer approaches based on Ag, Au, and Cu a suitable choice for detection applications.