No abstract

We demonstrate a novel application of a wavelength-swept fiber laser to fiber Bragg grating sensor-array interrogation. The laser provides high signal powers of >3 mW with <0.1-nm spectral resolution over a 28-nm wavelength span. Using time-interval counting, we demonstrate static-dynamic strain measurements with a resolution of 0.47mu? rms at a sampling rate of 250 Hz.

We demonstrate a novel all-fiber acousto-optic tunable notch filter based on coupling to cladding modes in a single-mode fiber. The device has the advantage of low loss (<0.1 dB) and low polarization dependence. By coupling input light to multiple cladding modes by use of multiple acoustic waves, we achieved an electronically controllable variable spectral profile without a significant coherent cross-talk problem.

The four complex, almost degenerate, second-order eigenmodes of a two-mode fiber having a circular core are reduced to two nondegenerate, linearly polarized second-order eigenmodes with stable-intensity lobe positions in a highly elliptical core fiber. Existing two-mode-fiber devices can be improved by this stabilization of the second-order modes. Practical sensors employing the two spatial modes as the two arms of an interferometer are described. The two arms of an interferometer of this type can have the same group delays, while the difference in phase delays is large.

We demonstrate a new type of high-performance long-period fiber grating based on arc-induced periodic microbends. The fabrication method is simple and does not require special fibers. Flexibility in controlling the filter parameters makes it possible to produce arbitrary filter profiles by use of a simple apodization technique, which is difficult to do with conventional long-period gratings.