Temperature and strain independent torsion sensor using a Sagnac interferometer based on a suspended twin-core fibre
R. M. Silva, INESC Porto - Institute for Systems and Computers Engineering of Porto (Portugal); J. Kobelke, K. Schuster, IPHT-Jena - Institute of Photonic Technology (Germany); O. Frazão, INESC Porto - Institute for Systems and Computers Engineering of Porto (Portugal)
In this work, it is presented a Sagnac interferometric configuration based on a suspended twin-core fibre for sensing applications. Using the suspended twin-core fibre, the fringe pattern is due to the differential optical path of the light in the two cores associated with a refractive index difference of ~10-3, which indicates an advantage of this approach compared with those based on Hi-Bi fibres, namely the possibility to use a small length of suspended twin-core fibre. The sensing configuration was characterized for torsion, temperature and strain. Using the Fast Fourier Transform technique it is possible to obtain the measurand induced amplitude variations of the fringe pattern. The results obtained indicate the viability of a temperature and strain independent torsion sensor.
