Highly sensitive magnetic field sensor based on a polarimetric fiber laser assisted by a Terfenol-D bar

We propose a highly sensitive magnetic field sensor based on a polarimetric fiber laser and a Terfenol-D bar. The laser cavity is structured with a high birefringence Erbium-doped fiber (Hi-Bi EDF) and a pair of wavelength-matched fiber Bragg gratings (FBGs). To transduce the magnetic field variations, A Terfenol-D bar is strategically employed, stretching the sensing Hi-Bi EDF upon exposure to the external magnetic field. The induced stress on the Hi-Bi EDF subsequently triggers shifts in the polarimetric mode beat frequency (PMBF), which exhibit a direct and measurable correlation to the variations in the magnetic field intensity. The experimental results show that the proposed sensor features high sensitivity, linear response, and excellent repeatability. It is noteworthy that in three consecutive magnetic field testing experiments, the sensor achieved a magnetic field sensitivity of up to -7.83 MHz/mT in the linear range of 3-12 mT, which surpasses that of comparable sensors by at least one order of magnitude, demonstrating the superiority of this sensor in magnetic field sensing capability.