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Laser remote sensing represents a powerful technique for investigating many aspects of the environment ranging from probing the upper regions of the atmosphere to measuring the depths of the oceans. It has also been shown to be capable of mapping pollution and may be capable of monitoring crops for stress. Recent, advances in the technology may permit it to be miniaturized and used in new exciting ways.

When a fiber-optic intracore Bragg grating is subject to an appreciable strain gradient, its reflective spectrum will not only be shifted but also be distorted because of the chirp of the grating. We employed the J-matrix formalism to calculate the influence of different strain gradients on the reflective spectra of Bragg gratings and have undertaken experiments to test these calculations. The results of these experiments have confirmed that intracore Bragg gratings can be used to evaluate strain gradients and can be thought of as quasi-distributed strain sensors. This adds a new dimension to structural sensing, permitting measurements in any situation where strain gradients exist. It also provides a warning of any sensor/host debonding.