Experimental Study on High Temperature Characteristic of Sn-Doped Fiber Bragg Grating

Fiber Bragg gratings (FBGs) were fabricated in Sn-doped single mode quartz fiber by UV exposure through phase mask. Linearity and repeatability of the FBGs were studied at temperature from 25 °C to 600 °C. The results of the study showed that linearity of the FBGs by high temperature heat treatment was better than that of sensor without standing heat treatment, and its linear correlation coefficient at least reached 0.997. Every time heating curve and cooling curve almost overlapped. Heating curves almost overlapped at different times. Cooling curves also were similar to heating curves at different times. Meanwhile, high temperature stability of the FBGs was further researched at 500 °C. It was showed that the reflectivity of the FBGs almost was keeping unchanging in decline to a certain value which depended on the preparation process of the FBGs after being heated 5 h at 500 °C. Therefore, the Sn-doped FBGs have excellent temperature sensing properties. It is possible to make low cost FBG sensors by using Sn-doped single mode quartz fiber in order to measure high temperature.