Modal noise in single-mode fibers.
So-called single-mode fibers are generally bimodal in that they can propagate two modes with orthogonal polarizations. If both transverse offset and angular misalignment are present in a single-mode fiber connector, the loss will be mode dependent. Physical distortions of the fiber before a connector cause modal noise. It is shown that the signal-to-noise ratio caused in this way is of the same order of magnitude as in suitable multimode-fiber systems.
Heckmann
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