LSPR-based fibre optic sensor fabricated by laser annealing of thin gold films

A fibre optic sensor based on localized surface plasmon resonance (LSPR) is fabricated by transforming a thin gold film deposited on the sensor tip into gold nanoparticles (AuNPs) using the laser annealing technique. The reflected spectra of the sensor exhibit a strong LSPR peak between 600 and 650 nm. The sensor is capable of detecting refractive index (RI) changes within the tested range of 1.3 to 1.395. As the RI increases, clear wavelength shifts in the peak wavelength are observed. The sensor responds linearly to RI variations, achieving a sensitivity of -215.8 nm/RIU. SEM analysis confirms the successful formation of AuNPs, which are essential for the sensor’s high sensitivity and consistent performance. The fabricated sensor is cost-effective, easy to fabricate, and suitable for biochemical applications.