Multi-parameter optical fiber sensor based on the combination of double SPR and MZl for magnetic field, temperature, and salinity

An integrated optical fiber sensor, based on the synergistic interaction between the surface plasmon resonance (SPR) and Mach-Zehnder interference (MZI), for monitoring oceanic parameters of temperature, salinity, and magnetic field, was designed. The sensor structure consists of multimode fiber (MMF) − no core fiber (NCF)-MMF-hollow suspended core fiber (HSCF)-MMF. The external surfaces of NCF and HSCF are coated with silver. Moreover, the silver-plated HSCF is individually encapsulated with magnetic fluid (MF) for magnetic field detection. Test findings reveal that the proposed sensor exhibits high sensitivity of 0.606 nm/Gs (R 2 = 0.999), −0.825 nm/℃ (R 2 = 0.992), and 0.321 nm/‰ (R 2 = 0.992), in the range of 0–312.4 Gs, 5–45 ℃, 0–40 ‰, respectively. The sensor exhibits uncomplicated manufacturing procedures, superior performance, and three-parameter detection capabilities. This sensor plays a vital role in advancing the integration of sensor arrays with multiple parameters in marine settings, achieving high sensitivity and wide detection limits for various parameters in marine environments.