Cryogenic Temperature characteristics of Thermosetting Epoxy Resins coated FBG Sensors

The Fiber Bragg grating sensor (FBG) is a kind of optical fiber sensor, compared with the electric sensor, it has many irreplaceable advantages for aerospace applications. The challenge of FBG for cryogenic application is how to increase the sensitivity of bare FBG and reduce nonlinear error. Two different thermosetting epoxy materials were studied to recoat bare FBG and presented a specific packaging method for thermosetting coatings. The verification of the accuracy of the model that is used to describe the FBG coated with thermosetting polymers by comparing the calculated results with the warming-up experiment conducted in the temperature range of 120K-328K using epoxy coated FBGs and bare FBG has been conducted. The results show a great improvement of sensitivity and good linearity, and the model can also be used to predict the characteristics of FBG coated with epoxy resins at cryogenic temperature and determine the stability of the epoxy.