High-Precision Surface Plasmon Resonance (SPR)-Based Five-Parameter Optical Fiber Sensor for the Simultaneous Detection of Refractive Index, Temperature, Magnetic Field, Relative Humidity, and Voltage

A multifunctional optical fiber sensor based on surface plasmon resonance (SPR) is designed and demonstrated for the synchronous detection of refractive index (N), temperature (T), magnetic field (H), relative humidity (RH), and voltage (U). The device employs a 10-hole photonic crystal fiber (10-hole PCF) as the substrate. Gold (Au) films are deposited in the alternately distributed air holes, which are subsequently filled with the analyte (Anal), polydimethylsiloxane (PDMS), magnetic fluid (MF), polyvinyl alcohol (PVA), and E7 nematic liquid crystal (E7NLC), respectively. This sensor enables synchronous multi-parameter detection using a single segment of the optical fiber. Numerical analysis reveals that in the ranges of 1.32-1.38 RIU, 20-40 °C, 35-135 Oe, 30%-70%, and 180-260 V, the average refractive index sensitivity, temperature sensitivity, magnetic field sensitivity, relative humidity sensitivity, and relative voltage sensitivity are 4,490.34 nm/RIU, -8.05 nm/°C, 1.52 nm/Oe, -5.83 nm/%RH, and 4.25 nm/V respectively. Featuring a simple structure, the sensor achieves integrated 5-parameter sensing for the first time. The results reveal a novel concept for multi-physical field sensing with a single segment of optical fiber.