Profile dispersion characteristics in high-bandwidth graded-index optical fibers.

To study profile dispersion effects on transmission bandwidth in high-bandwidth graded-index fibers, baseband frequency responses of various graded-index fibers with different profile parameters have been characterized in the 0.78-1.50-microm wavelength range. The test graded-index fibers were made by the MCVD technique. Intrinsic intermodal dispersions of these fibers were determined using a combination of a GaAlAs laser and a grating monochromator, a mode-locked Nd:YAG laser, an InGaAsP/InP laser, and stimulated Raman scattering in a single-mode fiber as the light sources. Transmission bandwidth functional dependences on wavelength are presented. The transmission bandwidth of the individual fibers changed by more than 400% within the experimental spectral range. The maximum transmission bandwidth so far observed was 3.74 GHz.km at 1.225-microm wavelength for a fiber with 0.20 N.A. Transmission bandwidth spectra were compared with computer calculated results based on Olshansky's theory.