To overcome the difficulty in the detection of cracks in concrete, distributed optical fiber
sensors can be pre-embedded in structures. Based on the principle of crack detection using
distributed optical fiber sensing technique, the layout of optical fiber was discussed, the relationship
between light attenuation and crack width was investigated through tests in laboratory, and a semi-
empirical formula for light attenuation and crack width was obtained. In addition, the measures of
optical fiber sensor protecting in construction and their long-term stability and reliability in
structures were discussed.