Fiber Bragg Gratings as Temperature and Strain Sensors

A fiber Bragg grating (FBG) consists of a periodic modification in the refractive core index along a short section of a germanosilicate optical fiber. Photorefractive intracore fiber Bragg gratings are attracting intense interest because of their wide field of application: they can be used in telecommunication systems 1 – 4 for wavelength division multiplexing (WDM) devices, wavelength-selective couplers, switches, integrated laser cavities (where a pair of gratings acts as partial or total narrow-band reflecting mirrors), dispersion compensators, as well as in sensing systems,5 either as single element or in a quasi-distributed array. Due to their compatibility with the transmission medium and the relative ease of their fabrication, the use of FBG as sensors, together with existing fiber technology, opens up a whole range of new opportunities for novel applications in areas such as smart structures and materials.