Rayleigh scattering in an optical fiber is caused by non-propagating random fluctuations of medium density and temperature intrinsically present in silica. Such local fluctuations in material density are introduced during the fiber manufacturing and fiber doping process and frozen during solidification. When an optical wave propagates in a fiber, it gets scattered all over its length. A small part of this scattered signal is captured back into the fiber core and is guided backwards towards the source, which can be treated as the sensing signal.
One of the research interests of our group is distributed fiber sensing based on Rayleigh backscattering, phase-sensitive optical time domain reflectometry (ɸ-OTDR), in particular. It has simple system structure and high temperature/strain sensitivity, compared to BOTDA, which is used in Brillouin Sensing.
Our current research mainly focuses on refinement of the system, as well as exploring the sensing quantities beyond the conventional quantities (temperature and strain), with special-designed fibers, such as pressure, gas and so on.
- Soto M. A., Lu X., Martins H. F., Gonzalez-Herraez M., and Thévenaz L., “Distributed phase birefringence measurements based on polarization correlation in phase-sensitive optical time-domain reflectometers,” Opt. Express 23, 24923-24936 (2015).
- Zhang, L. D. Costa, Z. Yang, M. A. Soto, M. Gonzalez-Herraez and L. Thevenaz, “Analysis and Reduction of Large Errors in Rayleigh-based Distributed Sensor,” in Journal of Lightwave Technology. doi: 10.1109/JLT.2019.2917746 (2019)
- Zhang, M. Fisser, F. Yang, and L. Thévenaz, “Distributed hydrogen monitoring with phase-sensitive optical time-domain reflectometry,” in 26th International Conference on Optical Fiber Sensors, ThE17 (2018).