Open AccessMagnetic field measurement based on a fiber laser oscillation circuit merged with a polarization-maintaining fiber Sagnac interference structure
Author(s) -
Jing Tian,
Yi-wu Zuo,
Mei-jiang Hou,
Yang Jiang
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.419306
Subject(s) - optics , materials science , fiber laser , fiber optic sensor , optical fiber , physics , optoelectronics
A compact optical magnetic field sensor based on a fiber laser oscillator circuit merged with a Sagnac loop that contains a polarization-maintaining fiber (PMF) and a magnetostrictive rod is proposed. The combination of the PMF-Sagnac loop and fiber laser oscillation circuit significantly increases the signal-to-noise ratio of the reflection spectrum in the system, which is a mixed spectrum that includes interference fringes and lasers. For the proposed system, an erbium-doped fiber amplifier is used to provide gain, a dispersion compensating fiber is used to compensate for dispersion in the system, a PMF is inserted in the Sagnac loop as a microwave filter, while a section of the PMF is bonded to a magnetostrictive rod to achieve magnetic field sensing. The proposed system is shown experimentally to produce a fine reflection interference spectrum. The highest intensity reflection interference peak (from the laser) is over 40 dB with a -3 dB line-width of about 0.03 nm. The system can provide magnetic field sensitivities of 0.07 nm/mT and 0.076 nm/mT for sensor head lengths of 1 m and 2 m, respectively, and exhibits a stability of ±0.029 nm over 1 h. The proposed sensing system has advantages of low cost, high sensitivity, compact structure, and can produce a fine and stable reflection spectrum.