Abstract:
A multi-functional method and apparatus are disclosed for producing a low hydroxyl ion-containing core rod from a tube suitable for the production of low-water optical fibers. The method and apparatus combine the use of process steps of (1) hermetically sealing a tubular quartz handle of a tubular porous core preform to a tube used to feed the porous preform into a sintering furnace, (2) dehydration and sintering, and (3) elongation of the sintered preform under vacuum, all without exposing the preform’s central aperture surface to ambient atmosphere.
Abstract:
An improved flame-hydrolysis process is disclosed, for manufacturing large optical fiber core preforms, useful in the production of low water, single-mode optical fibers. In one feature of the invention, the preform is manufactured using a vapor axial deposition (VAD) apparatus to form an inner core and an outside vapor deposition (OVD) apparatus to form an outer core, wherein the VAD and OVD apparatus both are located within the same housing. In another feature of the invention, the concentration of a germanium dopant in the inner and outer cores is substantially uniform, but increases immediately adjacent the outer surface of the outer core. Further, the concentration of a fluorine dopant in a surrounding cladding layer decreases from a maximum value immediately adjacent to the outer core. These variations in dopant concentrations are selected to offset the effect on refractive index caused by diffusion of the germanium dopant while the preform is subsequently being processes.
Abstract:
A method and apparatus are described for manufacturing substantially water-free optical fiber preforms by an outside vapor deposition (OVD) process, using a multi-functional apparatus that combines a vertical glass lathe with an OVD sintering system in one machine frame. The method includes steps of flame-sealing a quartz sintering tube to the handle of a porous soot preform made by an OVD process, after its deposition mandrel has been removed. The sintering tube is held in a rotatable chuck and used to feed the preform into a sintering muffle and oven. The open end of this sintering tube is connected through a rotary union above the chuck to a valve assembly that can be used to feed dehydration and sintering gases into the sintering muffle and also to draw a vacuum after sintering has been completed. The apparatus thereafter is used to seal the sintered preform's central aperture by collapsing a section of the sintering tube outside the sintering environment, while the aperture still is under vacuum, without allowing the central aperture to be exposed to ambient atmosphere. The resulting tubular preform thereafter can be processed further by a conventional steps of elongation to form a solid core preform, adding clad glass, and drawing into optical fiber.
Abstract:
An improved flame-hydrolysis process is disclosed, for manufacturing large optical fiber core preforms, useful in the production of low water, single-mode optical fibers. In one feature of the invention, the preform is manufactured using a vapor axial deposition (VAD) apparatus to form an inner core and an outside vapor deposition (OVD) apparatus to form an outer core, wherein the VAD and OVD apparatus both are located within the same housing. In another feature of the invention, the concentration of a germanium dopant in the inner and outer cores is substantially uniform, but increases immediately adjacent the outer surface of the outer core. Further, the concentration of a fluorine dopant in a surrounding cladding layer decreases from a maximum value immediately adjacent to the outer core. These variations in dopant concentrations are selected to offset the effect on refractive index caused by diffusion of the germanium dopant while the preform is subsequently being processes.
Abstract:
A multi-functional apparatus is disclosed for producing a low hydroxyl ion-containing core rod suitable for the production of low-water optical fibers. The apparatus combines the process steps of (1) hermetically sealing a tubular quartz handle of a tubular porous core preform to a tube used to feed the porous preform into a sintering furnace, (2) dehydration and sintering, and (3) elongation of the sintered preform under vacuum, all without exposing the preform's central aperture surface to ambient atmosphere.