Temperature measurements in deployed optical fiber networks using single photon optical time domain reflectometry

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Technology
• Metrology

Background:

• Accurate temperature monitoring is crucial for the performance and longevity of deployed optical fiber networks.
• Existing methods may lack the sensitivity or range required for comprehensive in-situ characterization.
• Single photon level measurements offer enhanced precision for optical sensing applications.

Purpose of the Study:

• To demonstrate a novel approach for measuring average temperature changes in deployed optical fiber networks.
• To develop and validate a model correlating temperature variations with photon time-of-flight changes.
• To enable precise in-situ characterization of both quantum and classical optical fiber networks.

Main Methods:

• Utilized Optical Time Domain Reflectometry (OTDR) at the single photon level.
• Derived a physical model linking optical fiber temperature changes to the time-of-flight of reflected photons (-50 to 400 °C).
• Employed a pulsed 1550 nm laser and a Superconducting Nanowire Single Photon Detector (SNSPD) for measurements.

Main Results:

• Achieved temperature change measurement accuracy of 0.08 °C over kilometer distances.
• Successfully demonstrated temperature measurements in a live, dark optical fiber network in Stockholm.
• Validated the derived model for temperature-dependent photon time-of-flight shifts.

Conclusions:

• The single photon level OTDR approach provides a highly accurate method for in-situ temperature monitoring of optical fibers.
• This technique is applicable to a wide range of temperatures and distances relevant to deployed networks.
• Enables enhanced characterization and potentially predictive maintenance for critical fiber infrastructure.