Subcarrier-based path-integrating strain sensor array utilizing fiber Bragg gratings

A fiber optic sensor system capable of detecting the strain distribution in a long length of optical fiber containing a series of fiber Bragg gratings is described. The technique utilizes RF sub-carrier based determination of the optical propagation time between the grating elements, and wavelength division-based addressing of the individual FBGs in the system. The approach will have applications in structural strain monitoring where long gage length sensing is required at multiple locations.