High sensitivity fiber Bragg grating (FBG) sensor based on hollow core silica tube (HCST) sensitization for gas pressure and temperature discrimination

摘要

A fiber Bragg grating (FBG) based sensor is proposed for the measurement of gas pressure under extreme tem-perature condition. Two FBG sensors of different cladding diameters are encapsulated and sealed in a fine hollow-core silica tube (HCST) by using a high temperature resistant ceramic adhesive (HTA). In the observation, the FBG sensors are practically insensitive to pressure change at room temperature and their pressure sensitivities are negatively higher at higher temperature. This can be attributed to the temperature dependence of the HTA's Young's modulus. The findings show that the sensors have a maximum pressure and temperature sensitivity of-0.993 nm/MPa and 13.8 pm/degrees C for a pressure range of 0-1 MPa over the temperature range of 17-400 degrees C. Despite the high pressure-temperature cross sensitivities, an interesting approach based on a 2 x 2 character-istics matrix is demonstrated for discriminative measurement of pressure and temperature