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

• A novel hollow suspended core fiber sensor enables simultaneous ocean magnetic field, temperature, and salinity measurement. • Hybrid effects of surface plasmonic resonance and interference were generated to achieve sensing of multiple parameters. • This sensor has excellent performance, with sensitivities of 0.606 nm/Gs, −0.825 nm/°C, and 0.321 nm/‰ in the given ranges. 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.