Fiber optic sensor counts photons to determine temperature

Nov. 23, 2011

Edinburgh, Scotland--A fiber optic temperature sensor offering a unique combination of high spatial resolution, accurate temperature determination, and fast readout has been demonstrated by researchers at Heriot-Watt University and the National Institute of Standards and Technology (NIST; Boulder, CO). A pulse of infrared light is launched into a test fiber and the faint return signal produced by Raman scattering is sampled at the single-photon level using high performance superconducting nanowire detectors.

By comparing the weak Raman scattering signals at frequencies above and below the launch frequency, the temperature can be extracted. The temperature profile along the fiber can be determined via a time of flight method exploiting the high timing precision of the superconducting detectors.

This measurement technique holds promise for practical temperature monitoring, says Mike Tanner at Heriot-Watt University: "The temperature along the fiber can be determined with centimeter precision and a temperature uncertainty less than 3 K in readout intervals under 1 minute. This technique is potentially useful for monitoring temperatures in large structures such as buildings and pipelines, or in mechanical objects with moving parts."

Furthermore, this technique is an advance in absolute temperature metrology. Shellee Dyer at NIST adds, "If the properties of the detectors, filters, and optical fiber are known, this system could potentially be used as a primary reference standard, providing accurate measurements without any external temperature calibration."

This work is reported in Applied Physics Letters 99, 201110 (2011), High-resolution single-mode fiber-optic distributed Raman sensor for absolute temperature measurement using superconducting nanowire single-photon detectors.

SOURCE: Heriot-Watt University

About the Author

Conard Holton | Editor at Large

Conard Holton has 25 years of science and technology editing and writing experience. He was formerly a staff member and consultant for government agencies such as the New York State Energy Research and Development Authority and the International Atomic Energy Agency, and engineering companies such as Bechtel. He joined Laser Focus World in 1997 as senior editor, becoming editor in chief of WDM Solutions, which he founded in 1999. In 2003 he joined Vision Systems Design as editor in chief, while continuing as contributing editor at Laser Focus World. Conard became editor in chief of Laser Focus World in August 2011, a role in which he served through August 2018. He then served as Editor at Large for Laser Focus World and Co-Chair of the Lasers & Photonics Marketplace Seminar from August 2018 through January 2022. He received his B.A. from the University of Pennsylvania, with additional studies at the Colorado School of Mines and Medill School of Journalism at Northwestern University.