Wide-Range Refractive Index SPR Sensor Based on Hexagonal Hybrid Plasmonic Waveguide

A wide-range refractive index (RI) surface plasmon resonance (SPR) sensor has been proposed, utilizing the metal-insulator–semiconductor hybrid plasmonic waveguide (HPW), having a unique hexagonal-shaped cross-sectional waveguiding structure. Chemical/bio-sensing applications typically require a broad-spectrum sensor with excellent sensitivity. The current work has addressed the necessity of a ubiquitous sensor with a wide range of RI sensing applications. The proposed sensor structure has been investigated with the help of finite-element method (FEM). Furthermore, encrusting all the slanted metal surfaces of the proposed SPR hexagonal-shaped sensor structure with a suitable semi-metal layer, such as graphene, has demonstrated the enhancement of the surface field and improvement in sensitivity. The extensive simulation by varying the different geometrical parameters as well as the wavelength has raised the average sensitivity of the proposed sensor, up to 750.89 nm/RIU, while the figure of merit (FOM) and Q-factor have been achieved, respectively, as 22.02/RIU and 34.63. The structure has been further analyzed from the fabrication point of view, where the ideal and two probable fabricated structures have been investigated.