All-fiber multipath Mach-Zehnder interferometer based on a four-core fiber for sensing applications

摘要

A novel, simple and compact optical fiber sensor based on multipath Mach-Zehnder interferometer (m-MZI) is proposed and experimentally demonstrated. The device consists of a segment of four-core fiber (FCF) spliced between two single-mode fibers (SMFs). When the m-MZI is kept straight, an obvious interference pattern appears in the transmission spectrum. Compared with previously reported optical fiber modal interferometers, higher phase sensitivity can be obtained in our scheme due to the multipath interference configuration embedded in one fiber. The maximum fringe visibility of the interference resonance dips exceeds 23 dB. The interference fringe of the FCF would shift with the variation of strain, temperature, refractive index (RI) and curvature. So it is possible to measure these parameters by simply monitoring the wavelength shifts. Experimental results show that the sensitivities of the sensor in strain, temperature, RI and curvature are 1.78 pm/mu e, 209 pm/degrees C, 91.39 nm/RIU and 20.18 nm/m(-1), respectively. To the best of our knowledge, the multi-purpose sensing applications of the sensor have been experimentally investigated for the first time. Moreover, the proposed sensor has the advantages of high fringe visibility and simple fabrication process. (C) 2016 Elsevier B.V. All rights reserved.