title: Optical Fiber Temperature and Torsion Sensor Based on Lyot-Sagnac Interferometer.
abstract: An optical fiber temperature and torsion sensor has been proposed by employing the Lyot-Sagnac interferometer, which was composed by inserting two sections of high-birefringence (HiBi) fiber into the Sagnac loop. The two inserted sections of HiBi fiber have different functions; while one section acts as the temperature sensitive region, the other can be used as reference fiber. The temperature and twist sensor based on the proposed interferometer structure have been experimentally demonstrated. The experimental results show that the envelope of the output spectrum will shift with the temperature evolution. The temperature sensitivity is calculated to be -17.99 nm/°C, which is enlarged over 12 times compared to that of the single Sagnac interferometer. Additionally, the fringe visibility of the spectrum will change due to the fiber twist, and the test results reveal that the fringe visibility and twist angle perfectly conform to a Sine relationship over a 360° twist angle. Consequently, simultaneous torsion and temperature measurement could be realized by detecting the envelope shift and fringe visibility of the spectrum.
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. lyshao@home.swjtu.edu.cn.
authors: Li-Yang
authors: LY
authors: Shao
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. xpzhang@home.swjtu.edu.cn.
authors: Xinpu
authors: X
authors: Zhang
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. haijunhe@my.swjtu.edu.cn.
authors: Haijun
authors: H
authors: He
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. zhiyongzhang@home.swjtu.edu.cn.
authors: Zhiyong
authors: Z
authors: Zhang
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. zouxihua@home.swjtu.edu.cn.
authors: Xihua
authors: X
authors: Zou
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. bluo@home.swjtu.edu.cn.
authors: Bin
authors: B
authors: Luo
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. wpan@home.swjtu.edu.cn.
authors: Wei
authors: W
authors: Pan
authors: Center for Information Photonics & Communications, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756, China. lsyan@home.swjtu.edu.cn.
authors: Lianshan
authors: L
authors: Yan
keywords: Lyot-Sagnac interferometer; fiber sensor; high-birefringence fiber; temperature and torsion sensor