Design and analysis of a gold-coated side-polished dual slotted channel PCF-SPR sensor for high-precision glycerine concentration detection

In this work, a highly sensitive and simple photonic crystal fiber (PCF) based surface plasmon resonance (SPR) refractive index (RI) sensor for glycerin concentration detection is presented and analyzed. In this design, a dual-polished slotted channel geometry is introduced. Gold (Au) is chosen as the plasmonic medium to enhance the SPR effect. The plasmonic material and the target analyte are positioned on the exterior of the sensor surface to ensure feasible operation. The proposed design features fourteen larger and ten smaller circular air-holes symmetrically distributed around the core, ensuring feasible fabrication. The sensor performance is quantitatively examined by employing the full-vector finite element method (FEM). To achieve optimum sensor performance, the structural parameters: lattice pitch, air-hole diameter, and thickness of the plasmonic material are systematically optimized. Simulation results show that the optimized sensor has attained a highest wavelength sensitivity (WS) of 68,000 nm/RIU, amplitude sensitivity (AS) of 2540.782 \({\text{R}\text{I}\text{U}}^{-1}\) , sensor resolution (SR) of 1.47 × 10^− 6 RIU for x-polarization with a broad detection range of 1.33 to 1.42. Additionally, the proposed sensor has been methodically analyzed for glycerine concentration detection across a wide range of 0% to 65%, demonstrating a WS of 88,590.60 nm/RIU and an AS of 2312.354 \({\text{R}\text{I}\text{U}}^{-1}\) , hence reflecting its significant potential as a credible medium for precise monitoring of glycerine concentration alongside other organic chemical compounds in pharmaceutical, biomedical, and industrial applications.