Temperature-dependent strain and temperature sensitivities of fused silica single mode fiber sensors with pulse pre-pump Brillouin optical time domain analysis

This paper reports a distributed temperature and strain sensor based on pulse pre-pump Brillouin optical time domain analysis. An uncoated, telecom-grade fused silica single-mode fiber as a distributed sensor was calibrated for its sensitivity coefficients under various strains and temperatures up to 800 °C. The Brillouin frequency of fiber samples changed nonlinearly with temperature and linearly with strain. The temperature sensitivity decreased from 1.113 to 0.830 MHz /°C in the range of 22–800 °C. The strain sensitivity was reduced from 0.054 to 0.042 MHz / με as the temperature increased from 22 to 700 °C and became unstable at higher temperatures due to creep effect. The strain measurement range was reduced from 19 100 to 6000 με in the temperature range of 22–800 °C due to fused silica’s degradation. The calibrated fiber optic sensor demonstrated adequate accuracy and precision for strain and temperature measurements and stable performance in heating–cooling cycles. It was validated in an application setting.