Pulse distortion in the ultimate multimode optical fiber

The shape of the impulse reponse of a step index, multimode fiber of circular cross section with material limited by Rayleigh scattering only is nearly invariant with fiber length L, unless L is so large that the signal has suffered an enormous scattering loss. The percent fraction of pulse energy responsible for distortion by scattering approximately 8.63 (1 - n(2)(CL)/n(2)(CO)) W(dB), where W(dB) is the associated energy reduction in decibels due to scattering from the core, and n(CL), n(CO) are the refractive indexes of cladding and core, respectively. WdB is nearly equal to length in kilometers for highly transparent material.