Helical sensor for simultaneous measurement of torsion and temperature. (February 2023)

• Record Type: Journal Article
• Authors: Lu, Chupeng; Zeng, Fei; Rui, Zeju; Xiang, Zihang; Geng, Tao; Sun, Cuiting; Yuan, Libo
• Is Part Of: Optics & laser technology. Volume 158:Part A(2023)
• Publication Date: 2023-02
• Subjects: Single mode fiber -- Long period fiber grating -- Helical sensor -- Simultaneous measurement; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2022.108934
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: The proposed sensor only used CO2 laser and single-mode fiber (SMF), which results in significant cost savings. According to the survey results, methods to improve torsional sensitivity include using special fibers; enhancing elliptical birefringence; and increasing shear stress. The proposed sensor greatly improves the sensitivity at low cost. The proposed sensor cleverly combines the CO2 laser polishing and pre-twist which can introduce elliptical birefringence in the fiber to improve sensing performance. In this work, the effects of different pre-twist degrees on the fabrication process and performance were specifically analyzed, and the results were consistent with the simulation results. The proposed sensor has the ability to achieve simultaneous measurement of torsion and temperature. Therefore, the sensor has potential in practical applications in complex environments. Abstract: Based on our current research on long-period fiber gratings (LPFGs), we propose a novel fiber-based sensor for simultaneous measurement of torsion and temperature. The proposed sensor cleverly combines CO2 laser polishing with pre-twist that can introduce elliptical birefringence in the fiber to improve sensing performance. Through comparative measurement experiments, we investigate the torsion characteristic of the sensor and the effect of different degrees of pre-twist on it. Experimental results show that the highest torsion sensitivity of two resonant dips can reach 0.635 nm/(rad/m) and −0.654 nm/(rad/m) in the range of 0 rad/m − 12.6 rad/m, while in the range of −12.6 rad/m − 0 rad/m the sensitivities are 0.14 nm/(rad/m) and −0.083 nm/(rad/m) respectively due to inhomogeneous elliptical birefringence. Meanwhile, the temperature sensitivity of the two resonant dips are calculated to be 62.5 pm/°C and 66.8 pm/°C, respectively. Due to the different sensitivities of temperature and torsion, the matrix method can be used for simultaneous measurement of two parameters to ignore crosstalk. As a result, the proposed sensor shows competitiveness in practical engineering applications.