Localized surface plasmon resonance refractometer based on no-core fiber

A novel optical fiber refractometer based on localized surface plasmon resonance (LSPR) is presented. The sensor was prepared by splicing a short segment of no-core fiber (NCF) between two multimode fibers. A gold nanoparticles (AuNPs) film was self-assembled on the sidewall of the NCF. When LSPR peak wavelength is used to investigate the refractive index (RI), sensitivity of 121.88 nm/RIU (R² = 0.9107), 523.14 nm/RIU (R² = 0.983) with limit of detection 1.64× 10⁻³ RIU, 3.82× 10⁻⁴ RIU over the RI range of 1.33–1.37 and 1.37–1.42, respectively. When normalized transmittance is used to investigate the performance of the sensor, sensitivity of −279 %/RIU (R² = 0.9922) with limit of detection 4.61 × 10⁻⁵ RIU over the RI range of 1.33 −1.42.