Multi‑core fiber‑optic dual‑axis differential accelerometer with a broadly configurable operating range

This paper presents a miniature, dual-axis, widely tunable fiber-optic accelerometer based on a four-core fiber mechanically coupled to an inertial mass by the superelastic NiTi microwire. The proposed structure forms a compact spring–damper system with an adjustable eigenfrequency and acceleration sensitivity at the optical fiber tip. Four Fabry–Pérot interferometers are established within the structure, each being resolved by the designated core of the four-core fiber, enabling interferometric, differential and temperature-compensated two-dimensional inertial mass displacement sensing. Several devices with varying key dimensions were fabricated to validate the proposed design concept. The fabricated accelerometers exhibited eigenfrequencies ranging from 26.1 Hz to 11 kHz and static sensitivities from 3250 nm/g to 0.27 nm/g, with a noise floor as low as 80 µg/√Hz. Cross-axis sensitivity was found to be below 5%, while the output variation in both axes remained below 1% of the ±1 g measurement range over a temperature range of ΔT= 60°C. The proposed design is simple and straightforward, offering compactness, broadly configurable operating range, making it well suited for applications requiring small size, low mass, and electrically passive operation. ● Dual-axis optical fiber accelerometer, fabricated at the optical fiber tip. ● Simple and straightforward design, providing a broad tunable range of sensor performance parameters. ● Four-core fiber enables temperature-compensated, fully orthogonal dual-axis readout of inertial mass displacement. ● Fabrication and evaluation of multiple devices with varied performance parameters, demonstrating the advantages of the design.