Highly sensitive surface plasmon resonance refractive index sensor comprising micro-grooved single-mode fibers

Surface plasmon resonance (SPR) has many applications in optical fiber sensing. Herein, a single-mode optical fiber refractive index sensor based on the SPR is designed and analyzed. The sensor comprises micro-grooves etched on a single-mode optical fiber to fix the gold wire. This structure facilitates the energy exchange between the fiber core and the plasmonic mode on the metal, and the mechanical strength is improved. The influence of structural parameters on the sensing properties is assessed by the finite element method. The sensor can detect sodium chloride solutions with concentrations between 120 and 360 g/L and hemoglobin solutions in the concentration range between 0 and 100 g/L. The sensor can determine refractive indices in the range between 1.33 and 1.41 with a maximum wavelength sensitivity of 28,200 nm/RIU. Since the sensor offers high-sensitivity refractive index detection for multiple liquids, it has immense potential in biosensing.