Abstract

A magnetic field sensor with temperature insensitivity implemented by two fiber Bragg gratings (FBGs) structure is presented and experimentally demonstrated. In the proposed sensing probe, a Terfenol-D piece is bonded with the same type of two FBGs in different direction relative to magnetic field. Two center wavelengths of the notches of FBG filters are mainly determined by the magnetic field, and the two FBGs experience different magnetic-field-induced strain and the same thermal expansion, leading to the linear relationship between the wavelength drift difference and the magnetic field and temperature insensitivity. By monitoring the shift of the wavelength drift difference, the magnetic field measurement for thermal-insensitive interrogation of the magnetic field sensor can be realized. Owing to its compact and temperature independent advantages, the proposed sensor has potential application especially in the unstable direction of magnetic field. Moreover, the sensor can also serve the purpose of temperature measurement by monitoring one of the center wavelengths. The measured sensitivity of the magnetic field intensity of the proposed sensor is 8.77 pm/mT.

Highlights

  • Magnetic field sensors have attracted increasing interests due to its plenty of applications in navigation, vehicle, current detections, and information storage [1]

  • The sensor ignores the thermal effect of giant magnetostrictive material. For another method to reduce the effect of temperature on the measurement of magnetic field, [19] proposed two fiber Bragg gratings (FBGs) for simultaneous magnetic field and temperature measurement, and one of them is encapsulated in an alumina tube to compensate the ambient temperature variation

  • We report a temperature-insensitive magnetic field sensor based on two FBGs theoretically and experimentally, which is independent of the applied magnetic field direction and more integrated of the magnetic field measurement compare to traditional temperaturecompensated magnetic field sensor

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Summary

INTRODUCTION

Magnetic field sensors have attracted increasing interests due to its plenty of applications in navigation, vehicle, current detections, and information storage [1]. The sensor ignores the thermal effect of giant magnetostrictive material For another method to reduce the effect of temperature on the measurement of magnetic field, [19] proposed two FBGs for simultaneous magnetic field and temperature measurement, and one of them is encapsulated in an alumina tube to compensate the ambient temperature variation. For the proposed wavelength modulated fiber optic magnetic field sensor, two FBGs bonded on the magnetostrictive material are placed in the magnetic field to be measured. The key component in the proposed magnetic field sensor is illustrated, and the two FBGs have nearly the same center wavelength B .The magnetic field direction is parallel to the magnetostrictive direction of Terfenol-D. Based on the theoretical analysis mentioned above, the magnetic field can be measured accurately by monitoring the wavelength drift difference between the two FBGs with a wide range of temperature, and the temperature variation can be obtained. To test the hysteresis of the interrogating system, the sensing probe is placed at the center of two permanent magnets in a certain distance to ensure it will be in uniform magnetic field, and the magnetostriction direction of the Terfenol-D piece works in parallel with the magnetic fields

Experimental data Linear fitting
Linear fitting
Wavelength drift difference
CONCLUSION
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