Highly sensitive multicore fiber accelerometer for low frequency vibration sensing

Abstract

We report on a compact, highly sensitive all-fiber accelerometer suitable for low frequency and low amplitude vibration sensing. The sensing elements in the device are two short segments of strongly coupled asymmetric multicore fiber (MCF) fusion spliced at 180° with respect to each other. Such segments of MCF are sandwiched between standard single mode fibers. The reflection spectrum of the device exhibits a narrow spectrum whose height and position in wavelength changes when it is subjected to vibrations. The interrogation of the accelerometer was carried out by a spectrometer and a photodetector to measure simultaneously wavelength shift and light power variations. The device was subjected to a wide range of vibration frequencies, from 1 mHz to 30 Hz, and accelerations from 0.76 mg to 29.64 mg, and performed linearly, with a sensitivity of 2.213 nW/mg. Therefore, we believe the accelerometer reported here may represent an alternative to existing electronic and optical accelerometers, especially for low frequency and amplitude vibrations, thanks to its compactness, simplicity, cost-effectiveness, implementation easiness and high sensitivity.

Mode-division and spatial-division optical fiber sensors

“…Supermode interferometers have been demonstrated for sensing a variety of physical parameters, including high temperature [130,132], bending [26,44,133], vibration [48,134], refractive index [135], and distance [25].…”

“…Phase-shifted modal interferometers. The concept of phase-shifted modal interferometers was introduced in 2020 [134,140,141]. The idea consists of placing two supermode interferometers in series, but the interferometers must have a proper difference in their lengths.…”

Comparative In Situ Study of Dynamic Load Generated by Gravel Piles Measured by a Fiber-Optic Interferometer

“…This type of sensor can be embedded in multicore fibers for compactness [ 30 , 31 ]. This sensor can be used, for example, as an accelerometer to measure low-frequency vibrations [ 32 , 33 ]. The Michelson fiber-optic interferometer as a seismic sensor can also be found in articles regarding various applications, such as the vibration measurement of oil wells [ 34 ] or general use in seismic applications [ 35 , 36 , 37 , 38 ].…”

Twin-core fiber sensor integrated in laser cavity

“…2 b, which was used as sensor head in this work, when a broadband light is launched into the central core of the TCF and analyzed at its exit by a spectrometer, a series of maxima and minima appear in the spectrum. However, when the same SMF-TCF-SMF structure is interrogated in reflection 21 , 27 , 36 , 37 , the light travels back and forth through it and the normalized coupled power at the output becomes: …”

“…The spectral overlap of the broad peaks of C-band sensors generally constrains their use to single point measurements. To overcome this limitation, efforts such as cascading MCF segments have been made, at the expense of increasing the complexity and length of the sensor 26 , 27 . Anyhow, due to the attractive features of coupled MCF-based sensors, it would be of interest to develop a technique to improve their spectral efficiency and allow for multiplexing, making it possible their use as multipoint sensors for applications such as structural health monitoring.…”