Sampled Bragg gratings formed in helically twisted fibers and their potential application for the simultaneous measurement of mechanical torsion and temperature

We propose and demonstrate a novel type of sampled Bragg gratings by combining a helically twisted fiber and a Bragg grating. A comb-like spectrum with a series of harmonic narrow resonances is observed, and the influence of geometrical parameters on the resonances is studied. As a special application. the intrinsic nature of the device that contains the Bragg grating and helical fiber spectral responses permits the temperature to be detected from the former, whereas the mechanical torsion is extracted from the latter, suggesting a potential for the simultaneous measurement of these two parameters. The proposed configuration features simplification, easy fabrication. high flexibility, stability, and low cost, and therefore has good prospects for sensor applications, as well as other applications, such as multi-channel filters, distributed Bragg reflectors. etc. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement