Double-helix-shaped optical fibers as a route for high-torsion sensing

This work describes the development of a novel fiber optic structure composed of two wrapped silica single-mode optical fibers. This structure acts like an interferometer where light propagating in the core fiber interferes with light that has propagated in the cladding region. The structure was fabricated with a period of 3.8 mm, showing high sensitivity to torsion (≈ 0.46 rad/m), with direction discrimination. The key advantages of this technology lie in its high torsion sensitivity and its low temperature cross sensitivity (≈ 0.18(rad/m)/°C).