Distributed shape sensing using Brillouin scattering in multi-core fibers

• Published in: Optics express Vol. 24; no. 22; p. 25211
• Main Authors: Zhao, Zhiyong, Soto, Marcelo A., Tang, Ming, Thévenaz, Luc
• Format: Journal Article
• Language: English
• Published: United States 31.10.2016
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.24.025211

A theoretical and experimental study on the response of Brillouin scattering in multi-core optical fibers (MCF) under different curving conditions is presented. Results demonstrate that the Brillouin frequency shift of the off-center cores in MCF is highly bending-dependent, showing a linear dependence on the fiber curvature. This feature is here exploited to develop a new kind of distributed optical fiber sensor, which provides measurements of a distributed profile mapping the longitudinal fiber shape. Using conventional Brillouin optical time-domain analysis with differential pulse-width pairs, fully distributed shape sensing along a 1 km-long MCF is practically demonstrated. Experimental results show a very good agreement with the theoretically expected behavior deduced from the dependence of the Brillouin frequency on the strain induced by the fiber bending over a given core. The analysis and results presented in this paper constitute the first demonstration of distributed bending sensing, providing the cornerstone to further develop it into a fully distributed three-dimensional shape sensor.