Fiber optic temperature and strain sensor using dual Mach-Zehnder interferometers

A fiber optic temperature and strain sensor using dual Mach-Zehnder interferometers (MZIs) is proposed. The dual MZIs were fabricated by fusion splicing of two different fibers between two single-mode fibers. The two fibers of thin-core fiber and small-cladding polarization maintaining fiber were fusion spliced with a core offset. As the responses of the two MZIs are different in terms of temperature and strain, simultaneous temperature and strain measurement were experimentally validated by selecting two resonant dips in the transmission spectrum to construct a matrix. Experimental results show that the proposed sensors had the maximum temperature sensitivity of 66.67 pm/°C and the maximum strain sensitivity of -2.0p m/µε. The minimum discriminated temperature and strain of the two proposed sensors were 0.20°C and 0.71 µε, and 0.33°C and 0.69 µε, respectively. The proposed sensor has promising application prospects due to the merits of ease of fabrication, low costs, and good resolution.