Simultaneous Detection of Magnetic Field and Temperature Using Micro-Nanofiber Cascaded Fiber Bragg Grating Structure

The monitoring of magnetic field plays an important role in aerospace, industrial production, and other fields. A novel sensor for simultaneous detection of magnetic field and temperature (MFT) by taking advantage of the micro-nanofiber Mach Zehnder interferometer (MZI) is proposed. Micro-nanofiber is formed by tapering single-mode fibers (SMFs). Furthermore, the MZI is cascaded to fiber Bragg grating (FBG) for the simultaneous detection of temperature. The structure is encapsulated in a glass tube filled with magnetic fluid (MF) to measure magnetic field intensity (MFI). FBG monitors temperature during MFI detection for the purpose of temperature compensation. By detecting the transmission spectra of FBG and MZI, it is possible to achieve simultaneous measurement of MFT. Experimental results show that the magnetic field sensitivity can reach 0.175 nm/Oe in the range of 0–133.5 Oe. The temperature sensitivity of the sensor is −0.486 nm/°C in the range of 30 °C–60 °C. The sensing structure has a detection limit of 3.09 Oe for MFI and 0.471 °C for temperature. The sensor has the characteristics of high sensitivity and compact size and can be used for dual-parameter measurements, which has broad application prospects in the fields of power systems and electromagnetic environment monitoring.