Surface plasmon resonance sensor based on coupling effects of dual photonic crystal fibers for low refractive indexes detection

To achieve sensing of low refractive indexes (RIs) in the near-infrared region, a novel series-wound structure with dual gold nanowires is designed and the photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is investigated. Numerical simulation by the finite element method (FEM) reveals that the odd mode for y-polarization has better sensing properties due to the more prominent shift of the confinement loss peak. The PCF-SPR sensor can realize a broad range of detection for low RIs changing from 1.13 to 1.35. The maximum spectral sensitivity of 17500 nm/RIU and optimal resolution of 5.71 × 10−6 RIU are observed for RIs between 1.34 and 1.35. Thus, the proposed sensor can be applied in environmental engineering, biochemical analysis and healthcare fields due to its ultrahigh sensitivity for analytes with low RIs in the near-infrared region and fabrication simplicity.