Temperature-independent torsion sensor based on “figure-of-eight” fiber loop mirror

Ricardo M Silva,António B Lobo Ribeiro,Orlando Frazão

doi:10.1007/s13320-012-0082-3

Abstract

An interrogation sensor system combining the “figure-of-eight” fiber loop mirror using a single directional 3×3 fiber optic coupler was proposed. One fiber loop mirror was formed by inserting a length of high birefringent optical fiber at the input ports of the 3×3 coupler. Splicing the output ports of the 3×3 coupler between them created the other fiber loop mirror. The introduction of this second loop gave rise to two polarization states of light with the same frequency but different optical phase. The mechanical torsion sensing head was located at the second loop and was exhibited an average modulus torsion sensitivity of 7.9×10−4 degree/dB. The performance of the sensor was not affected by environmental temperature variations.

Highlights

Nanostrain measurements can be useful in specific applications such as geophysics engineering.Since the end of the 1980s, the fiber loop mirror (FLM) has been demonstrated as an attractive device for optical fiber sensing [1]
One fiber loop mirror was formed by inserting a length of high birefringent optical fiber at the input ports of the 3×3 coupler
When a section of the highly birefringent (HiBi) optical fiber was spliced inside the FLM, a path imbalance was introduced between the light that propagated along different polarization eigenaxes, and an interferometric channeled spectrum was observed at the output

Summary

Introduction

Nanostrain measurements can be useful in specific applications such as geophysics engineering.Since the end of the 1980s, the fiber loop mirror (FLM) has been demonstrated as an attractive device for optical fiber sensing [1]. Abstract: An interrogation sensor system combining the “figure-of-eight” fiber loop mirror using a single directional 3×3 fiber optic coupler was proposed. One fiber loop mirror was formed by inserting a length of high birefringent optical fiber at the input ports of the 3×3 coupler.

Results

Conclusion