Combined temperature and strain measurement with a dispersive optical fiber Fourier-transform spectrometer

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Abstract
We report simultaneous measurement of strain and temperature in single-mode optical fiber by broadband interferometry. A Mach–Zehnder interferometer, illuminated by a xenon-arc lamp, has a sensing element in one arm. Scanning an air path, generates interferograms that are calibrated by a monochromatic reference interferogram. Values of group delay and dispersion, obtained from the phase of the fast Fourier transform of the sampled interferogram, give strain and temperature through a well-conditioned matrix transformation without phase ambiguity. We obtained measurement ranges and resolutions of 1500 ± 12 μstrain and 25.0 ± 0.4 K using a 0.8-m sensing element.