Universal readout system for temperature, elongation and hydrostatic pressure sensors based on highly birefringent fibers

In this paper, we present a universal readout system, which can be used to decode polarimetric fiber-optic sensors based on highly birefringent fibers. All such sensors use the same sensing principle, relying upon the dependence of modal birefringence on different physical parameters. To register the measurand-induced phase changes between polarization modes, we use the coherence-addressing principle. This requires that the interrogated sensor be powered by a broadband source (superluminescent diode) and that the total optical path delay introduced by the sensor be balanced in the decoding interferometer. The system performance in decoding elongation, temperature and hydrostatic pressure sensing is demonstrated.