Simultaneous measurement of torsion, strain and temperature using a side-leakage photonic crystal fiber loop mirror

A fiber optic sensor for simultaneous measurement of multi-parameter is proposed. The fiber sensor is realized by a fiber loop mirror based on a piece of homemade side-leakage photonic crystal fiber. Affected by the group birefringence of the side-leakage photonic crystal fiber, which induced by the elliptical germanium-doped core and the linear side-leakage defect, the fiber loop mirror has different wavelength responses to torsion, strain and temperature at different interference fringe valleys. By monitoring the wavelength shifts of three selected valleys in the transmission spectrum, simultaneous measurement of torsion, strain and temperature is achieved. The maximal sensitivities to torsion, strain and temperature are 151.14 pm/°, 1 pm/με and 71 pm/°C, respectively.