Wide index optical fiber sensor based on localized surface plasmon resonance

Abstract A wide refractive index (RI) photonic crystal fiber (PCF) sensor based on localized surface plasmon resonance (LSPR) was used to detect the RI of unknown analytes, and the modified sensor was numerically analyzed. The design features a D-type fiber structure with gold nanorods as the sensing layer, which enhances the mode matching between the core mode and the plasmon, thereby effectively promoting the LSPR effect. The results of the full-vector finite element method (FEM) analysis present that the displacement of core mode constraint loss peak is more obvious in Y-polarized mode. The wavelength sensitivity and figure of merit (FOM) are used to better and more accurately evaluate and analyze the output characteristics of the sensor. The results present that the sensor has a maximum wavelength sensitivity (WS) of 26,000 nm/RIU, a resolution of 3.85×10-6 RIU, a maximum FOM of 123.6, a sensor RI range of 1.02~1.39, and excellent transmission characteristics. The sensor has a simple structure and low cost, and its wide RI range has great application potential in molecular biology detection, environmental pollution detection, food safety detection, and drug research.