A long-haul optical transmission link is to be designed under the design constraints that (i) the radius of the core is to be no smaller than 4 ?m, and (ii) a numerical aperture (NA) of at least 0.12 is needed to focus optical energy into the fiber.
(a) What is the largest possible range of wavelengths for which single-mode operation occurs?
(b) Suppose unchirped Gaussian pulses at f = 1:55 m are used to transmit binary data. You're given that the fiber dispersion parameter ? = 17 ps/km-nm, and the dispersion length LD = 115 km. What is the half-width of the pulse at the origin? What is the distance it must travel for its width to be doubled?