Abstract

In this work, characterization of a Circular Core-Square Side Hole fiber (CC-SSHF) based on a Fiber Loop Mirror (FLM) for simultaneous measurement of temperature and strain is presented. The sensing head is comprised of 50 cm lengths of a 1.8 m length CC-SSHF inserted in FLM configuration. The induced birefringence of CC-SSHF is different for various wavelength spacing. Axial strain test reveals that this configuration shows positive strain sensitivity coefficients in range of 0 to 700 µε. The strain sensitivity coefficients for different dips are 11.08 pm/µε and 7.91 pm/µε. However, this structure shows negative temperature sensitivity coefficients in temperature analyzing experiment, which are equal to−0.366 nm/ ^°C and−0.654 nm/ ^°C. Considering the resolution of our interrogation unit, which is 2.5 pm, the sensor shows axial strain and temperature resolutions 0.22 µε, 0.31 µε, 0.006 ^°C and 0.003 ^°C respectively. The different sensitivities to the axial strain and temperature enable us to implement simultaneous sensing of axial strain and temperature. In addition, this structure can be a feasible sensor head for simultaneous measurement applications by considering the condition number of sensitivity coefficient matrix.

© 2018 The Author(s)