Fiber Bragg grating sensor for the simultaneous measurement of stress and temperature in high temperature environment

摘要

A novel fiber Bragg grating sensor operating in the environment of high temperature is studied. And the sensor can realize the simultaneous measurement of stress and temperature. The sensing head is comprised of one metal strip, one adiabatic strip and two FBGs with the same specification. The metal strip converts the measured temperature into the strain of the FBG2, and the temperature will be related to the peak wavelength shift of the FBG2 induced by the strain. The sensed stress in the environment of high temperature is transferred into the longitudinal strain applied into the FBG1 and FBG2 through the adiabatic strip and the metal strip, respectively, which will induced the peak wavelength shifts of the two fiber Bragg gratings. In this way, we can know the stress according to the center-wavelength shift of the FBG1, and the temperature from the difference of the peak wavelength between the FBG1 and FBG2. Finally, by a simple simulation we proved the physics feasibility of the sensor and found the fiber Bragg grating sensor has a stress sensitivity of about 0.15pm per N, and a temperature sensitivity of about 4pm per degree centigrade. A temperature dynamic range of 900 °C can be obtained.