Distributed fiber high-temperature sensing based on BOTDA (invited)

In this paper, the high temperature sensing properties of single-mode fiber, photonic crystal fiber, and gold-coated fiber at 1100 ℃, 1200 ℃, and 1000 ℃ were studied based on Brillouin optical time-domain analysis (BOTDA). The fact of Brillouin frequency shift (BFS) hopping and the coating burning indicated that the silica fiber should be annealed to reach a thermally stable state. After annealing, the BFS of the three kinds of fibers increased with temperature nonlinearly. The coating of single-mode fiber and photonic crystal fiber burned at high temperatures. And the crystallization of silicon doped its mechanical strength, indicating that it can only be used as a one-time high-temperature sensor. The gold-coated fiber with a higher melting point and better hermeticity can maintain good mechanical strength after high-temperature annealing, so it is a reusable high-temperature sensor. The research in this paper showed the potential for high-temperature sensing applications such as temperature monitoring of turbine engines.