All-Fiber Two-Dimensional Inclinometer Based on Bragg Gratings Inscribed in a Seven-Core Multi-Core Fiber

We demonstrated an all-fiber 2-D inclinometer based on fiber Bragg gratings with the capability of measuring the azimuthal angle and the inclination angle, simultaneously. The sensor performance is theoretically optimized and experimentally investigated. Excellent agreement between simulated and experimental results was achieved. Through detection of the wavelength shifts of the fiber Bragg gratings inscribed in the central core and two outer cores of a seven-core multi-core fiber, minimum error of 0.0056° for the azimuthal angle, and 0.025° for the inclination angle, were obtained. The detection range of the former ranges from 0 to 360°, while the latter ranges from 0 to 90°. The fiber Bragg grating in the central core can be used for temperature-compensation. The proposed fiber sensor is easy to fabricate and robust, increasing its potential in practical applications.