Distributed fiber optics sensors for civil engineering infrastructure sensing

Distributed Fiber Optic Sensing (DFOS) is one of the promising tools for structure health monitoring. It can measure physical quantities (such as temperature, strain, and vibration) of the fiber continuously (say 5 cm interval) along its length for long distance (say 10 km) due to its low-loss characteristic. By attaching an optical fiber cable to a structure or embedding it inside a structure, it is possible to monitor the changes of ambient parameters of the structure. In this paper, the measurement principles and their state-of-the-art status in terms of their capabilities are discussed. The main advantage is its high sensitivity over large distances and the ability to interface with a wide range of measurands in a distributed manner. The systems provide thousands of “strain gauges”, “thermo-couples”, or “accelerometers” along a single fiber optic cable connected to or embedded in structures, which can then serve as a civil infrastructure nerve system. It can be applied to flexible geometries, providing the ability to design a whole range of sensors with tremendous information carrying capacity. DFOS can provide a highly effective monitoring system for both short and long term to realize our concept of “smart infrastructure”.