Simultaneous measurement of temperature and strain by a single fiber Bragg grating based on bending losses

Abstract:

Fiber Bragg grating (FBG) sensors are extensively used in various sensing applications due to their high sensitivity. However, they are inherently sensitive to both strain and temperature, a cross-sensitivity problem, making it impossible to simultaneously monitor these two parameters using the Bragg wavelength shifts of a single uniform FBG. In this study, we bend the FBG pigtail to cause bending loss. The peak power of the FBG is used as the second characterization quantity. Our experimental results show that the Bragg wavelength sensitivities to strain (Kε) and temperature (KT) are 0.17 pm/με and 16.5 pm/°C, respectively. Additionally, the peak power sensitivities to strain (Pε) and temperature (PT) are -0.00202 dBm/με and -0.06 dBm/°C, respectively. The linear correlation coefficients for these measurements are all above 0.996. In this way, it is possible to simultaneously measure both strain and temperature using a single uniform FBG.

Key words:FBG(fiber Bragg grating); cross-sensitivity; temperature; strain;