Optical fibers with truncated cores

摘要

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.

主权项

1. A multimode optical fiber comprising in cross section:
a core having a first portion that extends from a center of the cross section to a radius R1, the core having a refractive index n1 at the center of the cross section and a refractive index ns at R1; and an un-doped cladding surrounding and in contact with the core, the cladding having a refractive index nclad, wherein the cladding consists essentially of pure silica, wherein the first portion has an alpha core profile and a step region at R1 where the refractive index difference from the cladding of ns−nclad is at least 0.2(n1−nclad), and wherein n1−nclad is less than 0.03.