Research On The Temperature Sensitivity Characteristic Of Fiber Bragg Grating In Low-temperature Condition

Fiber Bragg grating is an excellent sensor. Compare with the traditional sensors, it has the advantage of high voltage insulation, anti-electromagnetic interference, safety in nature and can be multiplexed. Because of these advantages, nowadays FBG has been widely used in all kinds of places, such as bridges, constructions, electric power. However there is little research on the FBG applying in low-temperature conditions. The main works of the paper is as follows:1. Research on the temperature characteristics of the fused silica. Mainly focus on the research of thermal expansion and thermal-optic characteristics and we forecast that because of these self-feature, FBG will appear a nonlinear relationship with temperature in the low temperature region, and the sensitivity will reduce gradually.2. Under the existing experiment conditions, we build up a FBG low-temperature characteristics test platform based on the fiber optical sensing extension modules, ASE optical source, and low-temperature thermostat bath. The low temperature experiment demonstrates that nonlinear effect occurs in low-temperature conditions. The temperature sensitivity reduces gradually as well.3. Base on the I-shaped invar substrate, we make an Al packaged FBG which enhance the sensitivity effectively. We also take the low-temperature experiment for the packaged FBG. The experiment find that new packaged FBG still exist the nonlinear effect, however the turning point of the nonlinear effect has shift to lower temperature which indicate that we can obtain a much longer linear region by enhance the sensitivity of the FBG.