Thermal variation of absorption in Yb3+-doped silica fiber for high-temperature sensor applications

Rare-earth materials doped into low-loss silica fibers are of interest for temperature sensing applications since the absorption properties of such are temperature dependant. Such absorption properties have been studied in ytterbium doped silica fiber using relative absorption and cut-back techniques at temperatures between 77 and 1163 K in the wavelength range 800 to 1150 nm. The wavelength dependant thermal sensitivity varies from -0.012 to 0.033 dB/K for a standardized one meter long 1000 ppm-doped fiber. These significant changes in absorption with temperature have been attributed to homogeneous line broadening. The fibers investigated show excellent potential for use as the sensing element in intrinsic fiber-optic high-temperture sensors.