Remote vectorial vibration sensing based on locally stabilized Mach–Zehnder interferometers using multi-core fiber and optical phase-locking

We report on remote sensing of vectorial vibration based on locally stabilized Mach–Zehnder interferometers (MZIs) using commercial multi-core fiber (MCF). Hexa-MZIs with a shared common reference arm are constructed by a 7-core MCF to acquire remotely vectorial vibration. A set of corresponding local receivers consisting of optical phase-locked loops (OPLLs) for not only eliminating the impact of environmental perturbations but also maintaining the stable operation and relative stability among the MZIs, allows guaranteed stabilized remote sensing. It moreover ensures a linearized phase detection, and thus an improved sensing sensitivity and dynamic range. This way, by exploiting the symmetrically geometric distribution for the cores of 7-core MCF, the proposed all-fiber design can enable highly precise remote extraction of vibration in a vectorial manner with a simplified remote structure. We achieve vectorial remote sensing for vibrations with ∼0.1076° and ∼0.3603 µm precision for the angle and displacement, respectively, over 10 km.