Cascaded Fabry-Perot interferometer-regenerated fiber Bragg grating structure for temperature-strain measurement under extreme temperature conditions

• Main Authors: Tian, Qin, Xin, Guoguo, Lim, Kok Sing, He, Yudong, Liu, Ji, Ahmad, Harith, Liu, Xiaochong, Yang, Hang Zhou
• Format: Article
• Published: Optical Society of America 2020
• Subjects: QC Physics
• Online Access: http://eprints.um.edu.my/36337/

We demonstrated an optical fiber sensor based on a cascaded fiber Fabry-Perot interferometer (FPI)-regenerated fiber Bragg grating (RFBG) for simultaneous measurement of temperature and strain under high temperature environments. The FPI is manufactured from a similar to 74 mu m long hollow core silica tube (HCST) sandwiched between two single mode fibers (SMFs). The RFBG is inscribed in one of the SMF arms which is embedded inside an alundum tube, making it insensitive to the applied strain on the entire fiber sensor, just in case the temperature and strain recovery process are described using the strain-free RFBG instead of a characteristic due-parameter matrix. This feature is intended for thermal compensation for the FPI structure that is sensitive to both temperature and strain. In the characterization tests, the proposed device has exhibited a temperature sensitivity similar to 18.01 pm/degrees C in the range of 100 degrees C - 1000 degrees C and excellent linear response to strain in the range of 300 degrees C - 1000 degrees C. The measured strain sensitivity is as high as similar to 2.17 pm/mu epsilon for a detection range from 0 mu epsilon to 450 mu epsilon at 800 degrees C, which is similar to 1.5 times that of a FPI-RFBG without the alundum tube. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement