A high-finesse fiber optic Fabry-Perot interferometer based magnetic-field sensor

A high-finesse extrinsic Fabry-Perot interferometric sensor for the measurement of weak dc magnetic fields is demonstrated. The Fabry-Perot cavity is formed by aligning the fiber end-face and the TbDyFe rod end-face, and each end-face is coated by a mirror with a micro-lens. The length of the TbDyFe rod is changed by the variation of an applied dc magnetic field, leading a change of the Fabry-Perot cavity length. By interrogating the white-light interferometric spectrum, the wavelength of the resonant peak is tracked and the length of the Fabry-Perot cavity is obtained. The sensor exhibits a high sensitivity of 1510 nm/mT with a magnetic resolution of 25 nT. (C) 2015 Elsevier Ltd. All rights reserved.