Three-Dimensional Vector Accelerometer Using a Multicore Fiber Inscribed With Three FBGs

TL;DR: In this article, a fiber-optic three-dimensional vector accelerometer for vibration measurement based on fiber Bragg gratings (FBGs) inscribed with three cores of seven-core fiber by femtosecond laser with a phase mask is presented.

Abstract: We have designed, fabricated, and characterized a fiber-optic three-dimensional vector accelerometer for vibration measurement The accelerometer is based on fiber Bragg gratings (FBGs) inscribed with three cores of seven-core fiber by femtosecond laser with a phase mask Through monitoring the wavelength shifts of two of the seven cores, we obtain the vibration azimuthal angle and the acceleration in the XY plane by angle reconstruction and algorithmic calculation Similarly, by monitoring the wavelength shift of the core fixed along the Z-axis, we obtain the vibration acceleration in the Z-axis direction The full 3D vector information about the vibration signal is obtained by vector synthesis The accelerometer has achieved a working frequency bandwidth from 10 to 220 Hz with the maximum sensitivity of 355 pm/g, and the best azimuthal angle accuracy of 0269 $^\circ$ in the linear range of 0 $^\circ$ –100 $^\circ$ and 170 $^\circ$ –280 $^\circ$ Moreover, it is possible to increase the overall bandwidth, sensitivity and accuracy of the azimuth of sensors in the XY plane by adjusting the length of the optical fiber and adjusting mechanical parameters to increase the bandwidth and sensitivity of the sensor in Z-axis Such improvements will further enhance application to small-scale seismic surveys