Reflective-Type Multiparameter Sensor Based on a Paired Helical Fiber Gratings and a Trapezoid-Like Microcavity

A reflective-type fiber sensor allowing the simultaneous measurements of directional torsion, strain, and temperature is proposed and experimentally demonstrated, which is realized by using a paired helical long-period fiber gratings and a trapezoid-like microcavity (PHLPGs-TLMC). With aid of the proposed sensor, the crosstalk effects among torsion, strain, and temperature can be well distinguished. The measurement resolutions for such three parameters are 0.017 rad/m,
$2.1~\mu \varepsilon $
, and
$0.452~^{\circ }\text{C}$
, respectively, which are competitive to those of the fiber-based sensors. In comparison with the transmission-type sensors reported to date, the proposed sensor is particularly used in reflection, which provides more flexibilities for sensor’s installation and is suitable for real-time and in-site measurements also. The proposed sensor could be found potential applications in structural health monitoring of the buildings, the bridges, the ships, the aircrafts, and so on.