A fast two-parameter test system based on combined FBG

Strain and temperature are two main parameters in fiber grating system, while there are cross-sensitive problems. In order to obtain this two-parameter at the same time, and to reduce its influence, a test system based on combined FBG is designed. Based on different effect of different core diameter strain, a kind of FBG probe is studied. On the basis of calculating the relationship between wavelength offset and the strain and temperature, the correlation function is deduced, and the coupling mode of the probe and the coupling efficiency are analyzed. In the experiment, strain and temperature test were completed by using light source, transmission fiber, combined FBG and so on. The results show that the wavelength offset is basically the same when the FBG changes with temperature. However, the slope change is quite different when stress changes. Finally, the strain and temperature were tested under different conditions, and the response coefficients of FBG temperature and strain were calibrated. It can be seen that the simultaneous analysis of temperature and strain can be achieved by detecting wavelength offset of combined FBG. The design is no need to weld, taper and other complex technologies. It has simple structure, strong capacity expansion capability and has high application value.