title: High-sensitivity bend angle measurements using optical fiber gratings.
abstract: We present a high-sensitivity and more flexible bend measurement method, which is based on the coupling of core mode to the cladding modes at the bending region in concatenation with optical fiber grating serving as band reflector. The characteristics of a bend sensing arm composed of bending region and optical fiber grating is examined for different configurations including single fiber Bragg grating (FBG), chirped FBG (CFBG), and double FBGs. The bend loss curves for coated, stripped, and etched sections of fiber in the bending region with FBG, CFBG, and double FBG are obtained experimentally. The effect of separation between bending region and optical fiber grating on loss is measured. The loss responses for single FBG and CFBG configurations are compared to discover the effectiveness for practical applications. It is demonstrated that the sensitivity of the double FBG scheme is twice that of the single FBG and CFBG configurations, and hence acts as sensitivity multiplier. The bend loss response for different fiber diameters obtained through etching in 40% hydrofluoric acid, is measured in double FBG scheme that resulted in a significant increase in the sensitivity, and reduction of dead-zone.
authors.affiliation: Shaanxi Key Laboratory of Optical Information Technology, Ministry of Education, School of Science, Northwestern Polytechnical University, Xi’an 710072, China.
authors.forename: Abdul
authors.initials: A
authors.lastname: Rauf
authors.forename: Jianlin
authors.initials: J
authors.lastname: Zhao
authors.forename: Biqiang
authors.initials: B
authors.lastname: Jiang