Torsion sensor based on a figure-of-eight cavity fibre laser

Abstract

A figure-of-eight based fibre laser cavity is proposed for the measurement of torsion. In one of the loops a section of photonic crystal fibre is inserted, acting both as an optical filter and the sensing head. The laser emission depends on the optical filter polarization and length. A single lasing band is achieved with a full width at half maximum of ∼1.72 nm. The proposed sensor presents sensitivity to torsion of 7.13 pm/degree over a range of 180 •. This configuration can also be used to measure optical power variations. Besides, due to the properties of the optical filter this sensor presents low sensitivity to temperature.

Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review

“…Sagnac interferometers/loop mirrors can also be equipped with active fibers and an optical pumping system to form lasers that generate output frequency that is dependent on torsional twist/rotation of the sensing section as shown in [24,25]. …”

A vibration sensor based on a distributed Bragg reflector fibre laser

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Advanced fiber-optic acoustic sensors

“…[54]. The DBR sensing head was made of a linear laser cavity formed by two FBG gratings 20 cm apart from each other, written directly in a highly-doped Er 3+ -doped fiber [55]. The proposed configuration is schematically illustrated in Fig.…”