Fiber torsion sensor based on a twist taper in polarization-maintaining fiber.

A novel optical fiber torsion sensor head is proposed. A section of polarization-maintaining fiber (PMF) is spliced between single mode fiber (SMF), and a twist taper is fabricated by a commercial electric-arc fusion splicer in the middle of the PMF. The asymmetric characteristics are obtained by the twist taper so that a fiber torsion sensor with directional discrimination is fabricated. Due to the characteristics of the asymmetric structure, the torsion sensitivity for the twist rate from 0 rad/m to −8 rad/m reaches 2.392 nm/rad·m−1, and for the twist rate from 0 rad/m to 8 rad/m reaches 1.071 nm/rad·m−1 respectively.