Simultaneous measurement of temperature and strain based on SCF-based MZI cascaded with FBG.

A novel seven-core fiber (SCF)-based sensor capable of simultaneous measurement of temperature and strain was proposed and experimentally demonstrated. The sensor consists of a fiber Bragg grating (FBG) and a SCF-based Mach-Zehnder interferometer (MZI). The MZI is formed by splicing a short section of SCF between two single-mode fibers (SMFs), and in the meantime, two fiber tapers that act as light splitter and coupler are formed at both ends of the SCF by the fusion splicing method. In addition, the FBG with a central wavelength of 1547.98 nm is cascaded at the end of one fiber taper, and thus simultaneous measurement of temperature and strain can be realized. The experiment result shows that the SCF-based MZI is only sensitive to temperature and has the higher temperature sensitivity of 93.11 pm/°C, while the FBG is sensitive to temperature and strain with sensitivities of 11.46 pm/°C and 0.627/µε, respectively. The corresponding temperature and strain resolutions of the sensor are 0.21°C and 27.95µε, respectively. The proposed sensor has the advantages of simple fabrication and high repeatability and has potential applications in many fields such as engineering machinery and building structure health monitoring.