High-Sensitivity PCF-SPR Sensor Coated with an Au–TiO₂ Composite Film

A highly sensitive photonic crystal fiber sensor coated with a gold–titanium dioxide composite film and comprising two layers of air holes is designed and analyzed by the finite element method. The sensor has high sensitivity and a wide wavelength detection range. In the refractive index (RI) range of 1.36–1.43, the sensor shows a maximum wavelength sensitivity of 55000[Formula: see text]nm/RIU, an average sensitivity of 11571[Formula: see text]nm/RIU, a resolution of 1.81 × 10[Formula: see text] and a wavelength detection range between 580[Formula: see text]nm and 1500[Formula: see text]nm. The off-center core structure facilitates the interactions with the plasmonic film and enhances the light transmission efficiency. The sensor has promising potential in fields such as biosensing, virus detection and organic chemistry.