All-solid multi-core fiber-based multipath Mach-Zehnder interferometer for temperature sensing

A novel multipath Mach-Zehnder interferometer (m-MZI) is proposed and experimentally demonstrated, which is fabricated by fusion splicing a segment of all-solid multi-core fiber (MCF) between two sections of single mode fiber-28 with a well-controlled lateral offset at the splice points. Beam propagation method-based simulation results demonstrated light passing throw MCF from multiple paths. Experiments with different lengths of MCF were implemented to investigate our proposed m-MZI's response to temperature and strain. 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. A very high temperature sensitivity of 130.6 pm/A degrees C has been achieved, and the maximum strain sensitivity is less than 0.284 pm/mu I mu in all experiments. A record low strain-to-temperature cross-sensitivity of 6.2 x 10(-4) A degrees C/mu I mu has been realized, and it shows great significance of this in-fiber integrated multipath Mach-Zehnder interferometer in practical temperature sensing applications.