High-Sensitivity Fiber-Optic Thermomagnetic Sensor Based on Hollow Suspended Core Fiber

A dual-parameter fiber-based sensor was created through the combined use of Mach-Zehnder (MZ) interferometry and surface plasmon resonance (SPR), facilitating concurrent measurement of magnetic field intensity and environmental temperature. The sensing structure is primarily made up of MZI and SPR structures linked in parallel. MZ interference for temperature detection is generated by melting a hollow suspended core fiber in two multimode fibers; Gold coating is applied on the surface of the suspended fiber to excite the SPR effect, and magnetic fluid (MF) is coated on its surface for magnetic field sensing. Experimental studies have shown that when the magnetic field strength range is 9.08 - 24.14 mT and the temperature range is 5 - 45 °C, the magnetic field sensitivity of the sensor can reach 8.96 nm/mT (R2=0.992), and the temperature sensitivity is -1.070 nm/°C (R2=0.997). This sensor exhibits excellent sensitivity and a large range in synchronous monitoring of magnetic field strength and temperature field. At the same time, the influence caused by the spatial difference of the measurement position of the series sensor is suppressed. In addition, the sensor has a small size, simple structure, and excellent performance, providing new ideas for the integration and miniaturization of multi-parameter measurement sensors in complex environments, and it has universal applicability.