A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure

• Main Authors: Ji Xia, Fuyin Wang, Hong Luo, Qi Wang, Shuidong Xiong
• Format: Article
• Language: English
• Published: MDPI AG 2016-04-01
• Series: Sensors
• Subjects: magnetic field sensor; Fabry-Perot Cavity; magnetic fluid; Fiber Bragg Grating; temperature compensation
• Online Access: http://www.mdpi.com/1424-8220/16/5/620

Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas.