Pulse broadening caused by deviations from the optimal index profile

摘要: The excess pulse broadening caused by deviations from the optimal index profile is analyzed for multimode optical fibers. First-order perturbation theory used to evaluate effects of arbitrary perturbations having longitudinal spatial frequencies which are too low cause mode coupling. A simplified expression found in terms a double integral over weighting function. Weighting functions evaluated and calculate two kinds circularly symmetric perturbations, Gaussian-shaped bump or dip an oscillating perturbation. These affect significantly according position width transverse frequency more narrow bumps those located at larger core radii have greatest effect. For typical fiber, making 2–18 oscillations along radius significant increases broadening, while rapid negligible results indicate type degree control required keep below specified level.