High-performance vector bending and orientation distinguishing curvature sensor based on asymmetric coupled multi-core fibre.

Fibre optic technology is rapidly evolving, driven mainly by telecommunication and sensing applications. Excellent reliability of the manufacturing processes and low cost have drawn ever increasing attention to fibre-based sensors, e.g. for studying mechanical response/limitations of aerospace composite structures. Here, a vector bending and orientation distinguishing curvature sensor, based on asymmetric coupled multi-core fibre, is proposed and experimentally demonstrated. By optimising the mode coupling effect of a seven core multi-core fibre, we have achieved a sensitivity of - 1.4 nm/° as a vector bending sensor and - 17.5 nm/m as a curvature sensor. These are the highest sensitivities reported so far, to the best of our knowledge. In addition, our sensor offers several advantages such as repeatability of fabrication, wide operating range and small size and weight which benefit its sensing applications.