Simultaneous Measurement of Magnetic Field and Temperature Based on SMF-MMF-SMF-HCF-SMF Fiber Structure

An all-optical fiber magnetic field and temperature simultaneous measurement sensor based on single mode fiber (SMF)-multimode fiber (MMF)-SMF-hollow core fiber (HCF)-SMF structure is proposed. The sensing structure is sealed with a capillary tube infiltrated with magnetic fluid (MF). By varying the external magnetic field and temperature, the transmission spectrum of the sensor will change accordingly. The sensing structure transmission spectra for the variation of magnetic field and temperature are investigated. In the experiment, the magnetic field sensitivity of −0.865 dB/mT in the range of 47–60 mT and temperature sensitivity of 0.519 dB/°C in the range of 27 °C–43 °C are obtained, respectively. Our multimode interference (MMI)-typed optical fiber sensor has the advantages of easy manufacturing, simple structure, good mechanical properties, low cost, and high sensitivity. The simultaneous measurement of magnetic field and temperature eliminates their mutual interference. The proposed magnetic field sensor has potential applications in several fields, such as the electric power industry, geological prospecting, and marine magnetic exploration.