Polarization properties of interferometrically interrogated fiber Bragg grating and tandem-interferometer strain sensors

• Published in: Journal of lightwave technology 2006-04, Vol.24 (4), p.1787-1795
• Main Authors: Cranch, G.A., Flockhart, G.M.H., Kirkendall, C.K.
• Format: Article
• Language: English
• Subjects: Accuracy; Applied sciences; Birefringence; Bragg gratings; Capacitive sensors; Circuit properties; Decoding; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fiber gratings; Fiber-optic instruments; Fibers; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated optics. Optical fibers and wave guides; Interferometry; Mathematical models; Optical and optoelectronic circuits; Optical fiber polarization; Optical fiber sensors; Optical fibers; Optical instruments, equipment and techniques; Optical interferometry; optical noise; Optical polarization; Physics; Polarization; Sensor phenomena and characterization; Sensors; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Strain; strain measurement
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2006.871055

Lead sensitivity in low-coherence interferometric fiber-optic sensors is a well-known problem. It can lead to a severe degradation in the sensor resolution and accuracy through its effect on the fringe visibility and interferometric phase. These sensitivities have been attributed to birefringence in the various components. In the current work, an analysis of the polarization properties of fiber Bragg grating and tandem-interferometer strain sensors, using Stokes calculus and the Poincare/spl acute/ sphere, is presented. The responses of these sensors as a function of the birefringence properties of the various components under different illuminating conditions are derived. The predicted responses demonstrate very good agreement with experimentally measured responses. These models provide a clear insight into the evolution of the polarization states through the sensor networks. Methods to overcome the lead sensitivity are discussed and demonstrated, which yield a differential strain measurement accuracy of 18 n/spl epsiv//spl middot/rms for a fiber Bragg grating sensor.