A novel temperature-compensated method for FBG-GMM current sensor

A novel method to compensate for the temperature influence on magnetostrictive sensor is proposed. The sensor head, which consists of two fibre Bragg gratings (FBGs) with the same initial Bragg wavelength, is bonded to two pieces of giant magnetostrictive materials (GMMs) and then is placed in the equal but opposite bias magnetic fields, respectively. When the measured magnetic field is applied, one FBG suffers an elastic lengthening, and the other suffers an elastic shortening, which causes the two FBGs to shift separately to longer and shorter wavelengths. Because the temperature variation results in the same Bragg wavelength shifts, its influence can be removed by measuring the difference of the FBGs’ wavelength shifts. The experimental results prove the feasibility of this method. Moreover, when the measured current increase from −170 A to 170 A, the sensor has approximate linear variation from −0.3 nm to 0.3 nm.