LARGE CORE MULTIMODE OPTICAL FIBERS

摘要

The specification describes multimode optical fibers produced by improved methods that reduce the manufacturing cost. These methods may also be more efficient in terms of power loss. In one of the embodiments, the improved design has a large core of pure silica derived from a rod-in-tube method. In the embodiment, a down-doped cladding is produced by depositing fluorine-doped silica on the inside of a silica starting tube using isothermal radio frequency plasma deposition. The silica core is inserted and the starting tube collapsed. The silica starting tube is removed and optical fiber is drawn from the fluorine-doped glass coated silica rod.

主权项

1. Process for the manufacture of optical fiber comprising:
(a) heating an optical fiber preform to the softening temperature, and (b) drawing an optical fiber from the preform, the invention characterized in that the optical fiber preform is prepared by steps comprising: (i) forming by Isothermal RF Plasma Inside Deposition (IRFPID):
a down-doped glass cladding layer on the inside of an IRFPID silica starting tube, wherein the IRFPID comprises
(i′) placing the silica starting tube within a resonant coil of a plasma generator,(ii′) introducing a down-dopant-containing chemical reactant into the silica starting tube,(iii′) maintaining the internal pressure within the silica starting tube at less than atmospheric pressure,(iv′) energizing the resonant coil to create an isothermal plasma within the silica starting tube,(v′) heating the inner wall of the substrate tube,(vi′) depositing down-doped glass on the silica starting tube within only a narrow zone upstream of the created isothermal plasma without deposition occurring within the isothermal plasma and the narrow zone being no greater than 1% of the length of the silica starting tube, (ii) inserting a glass core rod into the IRFPID silica starting tube, (iii) collapsing the IRFPID silica starting tube onto the glass core rod to produce a first solid glass body having core material, and down-doped cladding material on the core material.