Directional Bend Sensing With Bragg Gratings in All Solid Bragg Fibers

Fiber Bragg gratings have been inscribed in all solid Bragg fibers by use of 800-nm femtosecond radiations, multiple attenuation dips are observed in the transmission spectrum. The spectral characteristics and bend responses of such gratings are investigated. The peak wavelengths of these dips show zero-sensitivity when the fiber is bent under a wide curvature, while the transmitted power exhibits different trends with high sensitivity and strong direction dependence. These proposed gratings are very attractive candidates for bend sensing and they show a real potential for applications in multiparameter sensors.