Miniature multicore optical fiber vibration sensor.

We demonstrate a compact and versatile interferometric vibration sensor that operates in reflection mode. To build the device, a short segment of symmetric strongly coupled multicore optical fiber (MCF) is fusion spliced to a single-mode optical fiber (SMF). One end of the MCF segment is cleaved and placed in a cantilever position. Due to the SMF-MCF configuration, only two supermodes are excited in the MCF. Vibrations induce cyclic bending of the MCF cantilever which results in periodic oscillations of the reflected interference spectrum. In our device, the MCF itself is the inertial mass. The frequency range where our device is sensitive can be easily tailored from a few hertz to several kilohertz through the cantilever dimensions.