Materials that feel pain - distributed strain sensing by optical fibers embedded in structures and materials

Optical fibers can act as a sensor for strain, pressure and so on, through its optical properties, such as scattering and propagation-modes coupling. By additionally applying a way to analyze distribution of these properties along the fiber, the fiber acts as nerve for materials and structures, in which the fiber is embedded. The fiber optic nerve can sense damages induced in the materials and structures. We have proposed an optical correlation domain technique with continuous lightwave. By applying the technique, for example, to fiber Brillouin distributed strain sensing, we have demonstrated 1 cm spatial resolution and 57 Hz sampling rate, which are 100 times and 104 times higher than the time domain techniques, respectively