title: 1200°C high-temperature distributed optical fiber sensing using Brillouin optical time domain analysis.
abstract: In this paper, up to 1100°C and 1200°C high-temperature distributed Brillouin sensing based on a GeO2-doped single-mode fiber (SMF) and a pure silica photonic crystal fiber (PCF) are demonstrated, respectively. The Brillouin frequency shift's (BFS) dependence on temperatures of the SMF and PCF agrees with a nonlinear function instead of a linear function, which is mainly due to the change of the acoustic velocity in a silica fiber. BFS hopping is observed in both kinds of fibers between 800°C-900°C in the first annealing process, and after that, the BFS exhibits stability and repeatability with a measurement accuracy as high as ±2.4°C for the SMF and ±3.6°C for the PCF. The BFS hopping is a highly temperature-dependent behavior, which means that a high temperature (>800°C) would accelerate this process to reach a stable state. After BFS hopping, both the SMF and PCF show good repeatability for temperatures higher than 1000°C without annealing. The process of coating burning of a silica fiber not only introduces a loss induced by micro-bending, but also imposes a compressive stress on the bare fiber, which contributes to an additional BFS variation at the temperature period of the coating burning (∼300°C-500°C).
authors.forename: Pengbai
authors.initials: P
authors.lastname: Xu
authors.forename: Yongkang
authors.initials: Y
authors.lastname: Dong
authors.forename: Dengwang
authors.initials: D
authors.lastname: Zhou
authors.forename: Cheng
authors.initials: C
authors.lastname: Fu
authors.forename: Juwang
authors.initials: J
authors.lastname: Zhang
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Lu
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Bao