Bending effects in optical fibers
Open Access
- 1 October 1984
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in Journal of Lightwave Technology
- Vol. 2 (5) , 617-628
- https://doi.org/10.1109/jlt.1984.1073659
Abstract
Mode coupling at bends in optical fibers supporting one or only a few guided modes is analyzed by considering the local normal modes for the corresponding straight waveguide. Matrix elements giving the strength of coupling between guided modes at a corner bend, and for coupling between guided modes and radiation modes, are calculated as a function of guiding strength for this "geometrical" effect. The correction to these matrix elements due to the longitudinal strain in a bent fiber is also determined. The increase in propagation constant for the fundamental mode of a fiber wrapped in a coil of constant radius is calculated from information on the coupling strengths and mode propagation constants. The phase shift and attenuation of the fundamental mode caused by a spatially periodic microbending of the fiber axis are also considered. Finally, potential applications of these effects in fiber-optic devices such as mode converters, phase shifters, switches, and sensors are discussed.Keywords
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