Characterization of a fiber Bragg grating in pure-silica-core and Ge-doped-core optical fiber under high-temperature strain

The characterization of a fiber Bragg grating in pure-silica-core and Ge-doped-core optical fiber is demonstrated under tensile strain at different temperatures. The peak wavelength of the fiber Bragg grating increases slowly under tensile strain of 1000 µε when the temperature exceeds a certain value. The wavelength response of the pure-silica-core fiber Bragg grating is less sensitive under the same high-temperature strain as compared with the Ge-doped-core one. The results show a little predominance for the pure-silica-core fiber Bragg grating in high-temperature strain sensing. The two kinds of fiber Bragg grating are capable of measuring temperatures of up to 800 °C, but it is recommended that strain measurements are conducted below 500 °C to ensure good stability and repeatability.