Double-formant surface plasmon resonance for refractive index sensing by anti-resonance fibers with high sensitivity and wide detection range

Owing to advances in the surface plasmon resonance (SPR) technology, sensors composed of photonic crystal fibers (PCFs) based on SPR have attracted extensive attention. Herein, a double-formant SPR refractive index sensor comprising the anti-resonant fiber (ARF) is designed and analyzed, which can be used to realized high sensitivity and wide detection range. SPR is excited by gold filling in the negative curvature tube and replaces the traditional coating process to reduce the difficulty associated with actual production. Finite element analysis indicates that the optimized ARF-SPR sensor can detect analytes in the refractive index range of 1.310–1.445 with a maximum wavelength sensitivity and amplitude sensitivity of 36400 nm/RIU and 2,573.33 RIU⁻¹, respectively. In addition, the minimum resolution and structural parameter sensitivity is 2.747 × 10^-6 RIU and 38 nm/μm. The maximum figure of merit (FOM) is 776.15 RIU⁻¹, and as the refractive index of the analyte increases, the length of the sensor decreases, which suggesting great potential in biochemical detection and geological exploration.