Temperature insensitive strain measurement based on a novel Mach-Zehnder interferometer with TCF-PMPCF structure

Abstract

A novel Mach-Zehnder interferometer (MZI) with thin core fiber (TCF) – polarization-maintaining photonic crystal fiber (PMPCF) structure for measurement of temperature and strain is proposed and demonstrated experimentally. The MZI is formed by splicing a section of TCF and a section of PMPCF with core offset between two sections of single mode fibers (SMFs). Three sensors with different PMPCF lengths are investigated and compared. Since cladding modes and core mode respond differently to temperature and strain changes, both values can be measured independently. The temperature and strain sensitivities can be achieved simultaneously through the demodulation matrix. For the wavelength-related measurement, the temperature and strain sensitivities are 8.81\u2009pm/°C and 2.98\u2009pm/µε, respectively. In addition, the influence of temperature cross-sensitivity is also analyzed. The proposed sensor offers several advantages such as low cost, simple manufacturing technology, and temperature insensitiveness, which can be further applied in practical sensing.