Highly Sensitive Directional Torsion Sensor Based on a Helical Panda Fiber Taper

A novel directional torsion sensor based on a helical taper is proposed and experimentally demonstrated. The helical taper was fabricated in panda polarization-maintaining fiber by electric-arc discharge of a fusion splicer and by rotating one end fiber clamp simultaneously. The optimal parameters of the taper are the waist diameter of $60.84~\mu \text{m}$ and the length of $700~\mu \text{m}$ . This torsion sensor has a sensitivity of −3.191 nm/(rad/m) in the twist rate ranges from 0 to 13.57 rad/m, which is relatively higher than the value so far reported. Then, the torsion sensor also has the ability to identify rotational direction. In addition, the helical taper is almost insensitive to temperature.