Abstract:According to the temperature sensing principle of the fiber optic temperature sensor and the stress characteristics of coating, the theoretical model of the thermal stress characteristics and its influence for sensing characteristics was established by using the characteristic matrix of thin film. The thermal stress-temperature characteristics of the three kinds of fiber, inculding sapphire fiber, pure silicon core fiber and multimode fiber, were compared by analyzing the thermo-optic effect and thermal expansion characteristics of the film and fiber. A thin film formula for high temperature sensing probe was designed. And the thermal stress-temperature characteristics of each film layer of the formula, as well as the critical load stress characteristics, were analyzed, thus the critical load stress value of the selected fiber can be determined. By simulating the spectral sensing characteristics under different stresses, it provides theoretical basis and support for the stability and reliability of sensor-sensitive probes, and improves the efficiency of sensor development.