This paper reports the performance of short-gage-length optical fiber sensors embedded in a reinforced concrete specimen. Embedded extrinsic Fabry-Perot optical fiber sensors, attached to steel reinforcement rods, were used to monitor local displacements and strain in a concrete cross-beam specimen. The strain data obtained from the fider sensors were compared with data obtained from collocated foil strain gages. Absolute extrinsic Fabry-Perot interferometric sensors, capable of measuring absolute displacement and strain, were embedded in a stee-reinforced concrete specimen. Loading experiments performed on this specimen also yielded absolute strain information. The specimen was cyclically loaded for more than I00000 cycles in this geometry and the sensors still provided quantitative strain information regarding this specimen,

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An in-line fiber polarizer is proposed and demonstrated. The attenuation of a single-mode fiber experiencing an axial periodic perturbation shows peaks at certain wavelengths, resulting from the power coupling between the guided mode and the cladding modes. When the fiber has significant linear birefringence, each of these peaks is split into two peaks. The fiber thus exhibits polarization-selective attenuation characteristics. An example of such a polarizer is demonstrated based on a highly birefringent fiber with a beat length of 1.3 mm. A 25-dB polarization extinction ratio is obtained, with an attenuation of 1.3 dB at an operating wavelength of 1177 nm.

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