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Proceedings Paper

Torsion sensor based on a high-birefringent Sagnac loop interferometer
Author(s): M. S. Ferreira; R. M. Silva; O. Frazão
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Paper Abstract

In this work, a high-birefringent Sagnac loop interferometer torsion sensor is presented. The sensing head is inserted between the output ports of a high-birefringent coupler and it is formed by a section of standard single mode fiber. The sensing head characterization is done for torsion, temperature and strain measurements. The spectral response of this sensing head presents two interferometers, which are dependent on the light polarization states. Interference occurs due to the different lengths of the coupler output arms. This configuration allows the exclusion of a polarization controller, since it is possible to manipulate directly the polarization of light that travels inside the coupler. When the sensing head is subjected to torsion, it is possible to observe a beat between the two interferometers. In this case, there is a simultaneous π/4 excitation of the two polarization states in the splices region. The torsion sensitivity is related to the sensing head length. The sensor response is periodic and the twist range can be from -2π to 2π. The sensor is unaffected by temperature and strain variations. This configuration is simple and when compared to the conventional configuration, the polarization controller is suppressed. The setup can be used in specific applications, such as in mechanical engineering.

Paper Details

Date Published: 26 July 2011
PDF: 6 pages
Proc. SPIE 8001, International Conference on Applications of Optics and Photonics, 80013T (26 July 2011); doi: 10.1117/12.890514
Show Author Affiliations
M. S. Ferreira, INESC Porto (Portugal)
R. M. Silva, INESC Porto (Portugal)
O. Frazão, INESC Porto (Portugal)

Published in SPIE Proceedings Vol. 8001:
International Conference on Applications of Optics and Photonics
Manuel Filipe Costa, Editor(s)

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