Accurate strain sensing based on super-mode interference in strongly coupled multi-core optical fibres

Abstract

We report on the use of a multi-core fibre (MCF) comprising strongly-coupled cores for accurate strain sensing. Our MCF is designed to mode match a standard single mode optical fibre. This allows us to fabricate simple MCF interferometers whose interrogation is carried out with light sources, detectors and fibre components readily available from the optical communications tool box. Our MCF interferometers were used for sensing strain. The sensor calibration was carried out in a high-fidelity aerospace test laboratory. In addition, a packaged MCF interferometer was transferred into field trials to validate its performance under deployment conditions, specifically the sensors were installed in a historical iron bridge. Our results suggest that the MCF strain sensors here proposed are likely to reach the readiness level to compete with other mature sensor technologies, hence to find commercial application. An important advantage of our MCF interferometers is their capability to operate at very high temperatures.

Interferometer based on strongly coupled multi-core optical fiber for accurate vibration sensing

“…To make an interferometer, a few centimeters of MCF are fusion spliced to standard telecommunications optical fiber [17][18][19][20]. The fabrication of the SMF-MCF-SMF structure; see Fig.…”

“…Here, we report an approach to build simple, hence cost-effective, vibration (and acoustic) sensors based on a strongly coupled multi-core fiber (MCF). The MCF comprises seven cores embedded in a pure silica cladding [17][18][19][20]. To fabricate interferometric vibration sensors, a short segment of the MCF is inserted into conventional single-mode optical fiber (SMF) via the well-established fusion splicing process.…”

“…To fabricate interferometric vibration sensors, a short segment of the MCF is inserted into conventional single-mode optical fiber (SMF) via the well-established fusion splicing process. The insertion loss is on the order of 0.1 dB [17][18][19][20]. The MCF segment has structured coating and is packaged with a piece than has a Vgroove.…”

Multicore fibers for sensing applications

“…In chapter 4, a highly sensitive strain sensor based on the MCF with an HS was proposed and demonstrated. The strain sensitivity is dozens of times higher than that of the sensors based on interferometers in MCFs [70,71,75,149]. The process of fabricating the HS in a non-twisted MCF was introduced in detail.…”

“…Cross-sectional image of the strongly-coupled MCF [75]. (e) Schematic diagram of the MI based on the strongly coupled MCF for vibration sensing [76] xi…”