Abstract: This invention involves optical fiber which supports essentially only a single guided mode, perhaps degenerate, at the transmission wavelength, usually between 0.6 and 1.7 microns. The index of refraction of the core material is graded in the radial direction so as to yield an optical fiber with very low total dispersion and therefore high bandwidth. Specific embodiments include, in addition to the low dispersion characteristic, improved field confinement, and therefore permit lower clad-to-core ratios then heretofore believed practical. Additional advantages which accrue as a result of the greater field confinement include lower cabling, microbending, and curvature-induced losses.