Intensity-modulated directional torsion sensor based on a helical fiber taper

A novel intensity-modulated directional torsion sensor based on a helical taper is proposed and experimentally demonstrated. The tapers are fabricated in standard single-mode fiber by electric-arc discharge, and by rotating one side fiber simultaneously. Experimental results show that the intensity of transmission peak changes inversely when the helical taper is twisted in clockwise and counterclockwise, respectively. The maximum torsion sensitivity can reach -0.484 dB/(rad/m) in the twist rate ranges from -10.67 rad/m to 0 rad/m. Additionally, this torsion sensor is almost insensitive to temperature, which solves the problem of torsion-temperature cross sensitivity greatly. The novel torsion sensor provides a promising candidate for the applications that require accurate rotation, such as civil engineering, the automotive industry, and security monitoring of buildings.