Compact omnidirectional multicore fiber-based vector bending sensor

Abstract

We propose and demonstrate a compact and simple vector bending sensor capable of distinguishing any direction and amplitude with high accuracy. The sensor consists of a short segment of asymmetric multicore fiber (MCF) fusion spliced to a standard single mode fiber. The reflection spectrum of such a structure shifts and shrinks in specific manners depending on the direction in which the MCF is bent. By monitoring simultaneously wavelength shift and light power variations, the amplitude and bend direction of the MCF can be unmistakably measured in any orientation, from 0° to 360°. The bending sensor proposed here is highly sensitive even for small bending angles (below 1°).

Twin-core fiber sensor integrated in laser cavity

“…To that end, the process described in Ref. 21 was replicated. The sensitivity of asymmetric MCFs as the one used in this work depends on the relation between the orientation of the cores and the plane in which the effect is applied 21 , 25 , 42 , 43 .…”

“… 21 was replicated. The sensitivity of asymmetric MCFs as the one used in this work depends on the relation between the orientation of the cores and the plane in which the effect is applied 21 , 25 , 42 , 43 . Thus, as vibrations were applied vertically, regarding the expected wavelength shift, TCF1 would have minimum sensitivity, whereas TCF2 would have maximum sensitivity.…”

“…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: …”

“…Thus, if we excite the TCF with a SOA whose pulses are tuned to the of the cavity (~ 10 6 Hz), the system will lase at , providing a unique, much sharper and narrower peak in the spectrum compared to the broad maxima and minima obtained when such MCFs are interrogated with a broadband light source 21 – 23 . This fact allows for multiple-peak clean-up, and using and multiplexing MCF-based devices with identical or similar spectra in the same interrogation window, as they are unmistakably and individually identified by the unique of each.…”

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

“…The three-dimensional interferometric system is used by the authors of publications [ 28 , 29 ], for example, to monitor seismic activity on the seabed. 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 ].…”