25 April 2006 Phase extraction in two mode birefringent optical fiber and its application in quasi-distributed strain sensing
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Abstract
A phase extraction technique based on data dependent system (DDS) method in higher order modal interference (LP01 and LP02) within the birefringent optical fiber is presented. A frequency modulated optical signal from a laser diode was launched into the fiber and the higher modes were excited. The interference patterns recorded at the output end of the fiber was digitized and characterized by means of autoregressive model. Self coherence function of an interferogram was obtained from the autoregressive parameters and this would provide the phase change due to the measurand. The modulation of group delay was obtained from the phase curve through unwrapping. An application has been made for measurement of strain in an array of simply supported beam and cantilever beam at different locations under different loading conditions. Results have been compared with those obtained using Fourier transform method and parametric method for different applied strain (200-2000 μstrain).
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S. K. Ghorai, Dilip Kumar, Soumya Sidhishwari, "Phase extraction in two mode birefringent optical fiber and its application in quasi-distributed strain sensing", Proc. SPIE 6189, Optical Sensing II, 61891X (25 April 2006); doi: 10.1117/12.662474; https://doi.org/10.1117/12.662474
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