Miniature Two-Axis Accelerometer Based on Multicore Fiber for Pantograph-Catenary System

We report a miniature and robust two-axis accelerometer using a cantilever beam structure based on a multicore fiber (MCF) for pantograph-catenary system monitoring. Two cores of the MCF were inscribed with fiber Bragg gratings (FBGs) using a femtosecond laser-based point-by-point technique without the need to remove the protective coating of the fiber. The parameters of the sensor have been optimized using finite-element-based simulations and its response to acceleration was investigated at a frequency of 40 Hz at different orientations. The packaged sensor has a weight of 5.2 g with maximum acceleration sensitivities of 18-19 pm/g along the $x$ - and $y$ -axes, respectively, for applied acceleration up to 10 g. Furthermore, the fabricated sensor exhibits a sensitivity of 14 pm/g along with a linear response for higher acceleration from 10 to 25 g, thereby demonstrating its robustness for practical applications that require small and lightweight accelerometers.