Appl. Phys. Lett. 99, 201110 (2011)

Distributed temperature sensing can be useful for monitoring structures such as buildings and pipelines. Michael Tanner and colleagues from Heriot-Watt University in the UK and the National Institute of Standards and Technology (NIST) in Colorado, USA, have now built a distributed fibre Raman sensor that can simultaneously measure absolute temperature at over 100 1.2-cm-spaced positions along a single-mode optical fibre. Although distributed fibre sensors have been around for a while, the researchers claim that previous research focused on using multimode fibres and avalanche photodiodes, which limited detection wavelengths to around 800–900 nm. In contrast, this latest work uses pulses of 1,550 nm light and measures the single-photon level Raman backscattered signal using superconducting nanowire single-photon detectors. The researchers used a time-of-flight approach to determine the temperature profile along the fibre. They recorded temperature measurements at various positions along the fibre with an uncertainty of less than 3 K over a period of 1 minute. They hope that a 1-km-range distributed sensor will be possible in the near future.