Optical fiber sensor for early warning of corrosion of metal structures

Long period fiber gratings (LPFGs) were over coated with iron (Fe) and subjected to oxidation in air and in solutions of water containing different sodium chloride (NaCl) concentrations. The formation of iron oxides and hydroxides was monitored in real time by following the features of the gratings attenuation band. Preliminary results show that Fe coated LPFGs can be used as sensors for early warning of corrosion in offshore and in coastal projects where metal structures made of iron alloys are in contact with sea or brackish water.