Temperature compensated fiber optic magnetic sensor based on the combination interference principle

In this paper, a highly sensitive temperature compensated fiber optic magnetic field sensor by Sagnac and Mach-Zehnder combination interference (SMZI) is proposed and verified. The sensing structure relies on microstructured exposed core fiber (ECF) filled with ethanol and magnetic fluid (MF). The refractive index of MF and ethanol is affected by the magnetic field and temperature (MFT). SMZI is based on the multimode and birefringence characteristics of ECF. The measurement principle is that the spectra of Sagnac interference and Mach-Zehnder interference have respective sensitivities to the Mil'. The magnetic sensitivity can reach 1.17 nm/mT, and the temperature sensitivity is up to -1.93 nm/degrees C. At the same time, the sensor has good repeatability and low detection limits of 0.41 mT and 0.25 degrees C, respectively. It not only solves the cross-influence of temperature but also makes the spectral analysis more intuitive. The sensor has a broad development prospect in the application of MFT detection. (C) 2022 Optica Publishing Group

Automated summary

This paper proposes and verifies a highly sensitive temperature compensated fiber optic magnetic field sensor using Sagnac and Mach-Zehnder combination interference (SMZI). The sensor relies on microstructured exposed core fiber filled with ethanol and magnetic fluid. It achieves high magnetic sensitivity and temperature sensitivity, with good repeatability and low detection limits.