Torsion sensor based on inter-core mode coupling in seven-core fiber

Abstract

We proposed a novel torsion sensor based on inter-core mode coupling in seven-core fiber (SCF). The torsion sensor is fabricated by tapering a commercially available SCF spliced with two single mode fibers. Waist diameter and length of the taper structure were experimentally optimized to achieve good transmission spectrum. Based on this structure, the torsion measurement was conducted, and the experimental results demonstrated that the transmission spectrum shows a red shift with the fiber twist. The torsion sensitivity increases with the twisting angle, which can achieve as high as 1.00 nm/°. The direction of wavelength shift was observed to be opposite when twisting the tapered SCF in clockwise and counter-clockwise direction, demonstrating its capability to discriminate the rotation orientation. Moreover, all the measurements were repeated in attempts to confirm its stable performance as well as high accuracy. Mode coupling dynamics and theory of optical anisotropy in twisted fiber are adopted to discuss the sensitivity performance, which agrees well with experimental results. The novel torsion sensor could provide a promising candidate for the applications requiring accurate rotation.

Nonlinear deformations of a cylindrical pipe with pre-stressed thin coatings

“…The symbol A × = A ks i k ×i s denotes the vector invariant of the second-rank tensor A = A ks i k ⊗ i s . In conformance with (21) and (22), stress and couple stress tensors of Piola type have the property n • D = n • G = 0. This relation is also satisfied by other tensors appearing in (21) and ( 22) except for the rotation tensor H.…”

“…First, it is a crucial way to determine the industrial reliability characteristics of these cables [19]. Analysis of the effect of torsion on optical characteristics allows the existing sensors to be improved and new sensors to be developed for the parameters of torsion and rotation [20, 21]. A nonlinear change in the fiber dielectric tensor caused by twisting leads to a change in the propagation constants of the core and cladding modes [22].…”

Experimental Approach for Complex Optical Fiber Angular Orientation and Twist Measurement

“…[32] The presented method can apply to multicore fibers used in shape and torsion sensors but is not suggested as a torsion or shape sensor and hence is not meant to replace general torsion sensing system. [33][34][35] In the following sections, we present the optical arrangement used for the orientation analysis of optical fibers. Typical measurements for different kinds of multicore fiber structures are shown, and the cross-correlation method for identifying different fiber orientations is explained.…”

Twisting measurement and compensation of optical shape sensor based on spun multicore fiber

“…Notwithstanding the vast amount of research conducted on shape sensing, this problem has not been addressed yet in an adequate manner. Tan et al developed a torsion sensor based on inter-core mode coupling by tapering a multicore seven-core fiber [27]. Notwithstanding the innovation of this approach, it cannot be employed for shape sensing, since the fiber structure becomes inhomogeneous due to the tapering.…”