Fiber optic Bragg grating technology offers unrivaled sensing versatility combined with the promise of extremely compact, rugged and low-cost integrated optoelectronic microchip demodulation systems. We show that a tunable laser can be used to demodulate each of the different sensing modalities: short and long gage fiber optic strain sensors; serial and parallel multiplexed fiber grating sensor arrays and truly distributed sensing based on intragrating strain profile mapping. We also show that distributed strain sensing is not limited by the length of a single Bragg grating. We demonstrate that Fourier transform analysis combined with tunable laser interrogation of a string of gratings permits distributed sensing over distances of about a meter without the need for high-cost time division multiplexing or producing each grating with a different reference wavelength as required by wavelength division multiplexing.
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Fiber Optic Smart Structures Laboratory, University of Toronto Institute for Aerospace Studies, 4925 Dufferin Street, North York, M3H 5T6, Ontario, Canada;
