Modal Dispersion in Step-Index Fibers
Determine the core radius of a multi-mode step index fiber with a numerical aperture NA = 0.1 if the number of modes M = 5000 when the wavelength is 870nm. If the core refractive index n_{1} = 1.445, the group index N_{1} = 1.456, and Δ is approximately independent of wavelength, determine the modal-dispersion response time σ_{T} for a 2-km-Iong fiber.