Abstract: Optical fiber designs are depicted with a core having an alpha profile inner portion and a steep vertical step between the core and a cladding with no shoulder, referred to herein as a truncated core. A further aspect of this invention can include a trench between the truncated core and cladding. In this embodiment, the core performs as not only as the primary light guiding structure, but now also functions essentially the same as that of a trench structure. Thus, what was formally a trench can now be much less negative or even positive. Another embodiment of the present invention includes an optical fiber having a truncated core with the addition of a ledge or shoulder between the core and vertical step, followed directly by a cladding.

Abstract: Optical fiber refractive index profile designs having an alpha core profile and a negative index trench to control bend loss, are modified by truncating the edge of the alpha core profile and adding a ledge to the truncated core. The result is low bend loss and preservation of low differential mode delay and high bandwidth.

Abstract: Optical fiber designs are depicted with a core having an alpha profile inner portion and a steep vertical step between the core and a cladding with no shoulder, referred to herein as a truncated core. A further aspect of this invention can include a trench between the truncated core and cladding. In this embodiment, the core performs as not only as the primary light guiding structure, but now also functions essentially the same as that of a trench structure. Thus, what was formally a trench can now be much less negative or even positive. Another embodiment of the present invention includes an optical fiber having a truncated core with the addition of a ledge or shoulder between the core and vertical step, followed directly by a cladding.

Abstract: Optical fiber refractive index profile designs having an alpha core profile and a negative index trench to control bend loss, are modified by truncating the edge of the alpha core profile and adding a ledge to the truncated core. The result is low bend loss and preservation of low differential mode delay and high bandwidth.

Abstract: An improved MCVD process reduces a rippling structure in the refractive-index profile of a graded-index, multiple-mode optical fiber by incorporating N2O, CO, or NF3 gas in the gas stream during deposition of a soot sub-layer from which the optical fiber is formed. The soot sub-layer is sintered to form a glass sub-layer during deposition of a subsequent soot sub-layer. A dopant species is incorporated in each soot sub-layer during deposition. Fibers made from the doped glass sub-layers have a graded refractive-index profile that is near-parabolic in shape and that has significantly reduced rippling compared to profiles observed for fibers prepared conventionally.