Torsion sensing setup based on a three beam path Mach-Zehnder interferometer

In this letter, a torsion sensing arrangement based on a three beam path Mach-Zehnder interferometer (MZI) is presented. The MZI with three beam paths was fabricated by fusion splicing a piece of double ytterbium-doped double-cladding photonic crystal fiber (Yb-d-DPCF) between two segments of single mode fiber (SMF). Moreover, in our sensing arrangement the Yb-d-DPCF segment is acting both as the MZI as the gain medium. Here, a spectral MZI fringe shifting is induced by applying torsion over the Yb-d-DPCF. By this setup, a torsion sensitivity of 0.001 nm/degrees was achieved. Finally, it is shown that the sensing arrangement is compact and robust. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1857-1860, 2015