Abstract: An optical fiber forming apparatus comprises: a draw furnace comprising: (i) a muffle with an inner surface, (ii) an axial opening below the muffle, the inner surface of the muffle defining a passageway extending through the axial opening, and (iii) an upper inlet into the passageway; and a tube that extends into the passageway of the draw furnace above the axial opening, the tube having (i) an outer surface and the inner surface of the muffle surrounds the outer surface of the tube with a space separating the outer surface of the tube from the inner surface of the muffle, (ii) an inner surface that defines a second passageway extending through the tube, (iii) an inlet into the second passageway of the tube, (iii) an outlet out of the second passageway of the tube.

Abstract: A method of processing an optical fiber includes drawing the optical fiber from a heated glass source, reheating the optical fiber, and cooling the optical fiber under vacuum at a cooling rate less than the cooling rate of the optical fiber in air at 25° C. and 1 atm. Cooling the optical fiber under vacuum is conducted after reheating the optical fiber. Cooling the optical fiber under vacuum reduces the rate of heat transfer from the optical fiber, which may enable further relaxation of the glass and reduction in the fictive temperature of the optical fiber. A system for processing an optical fiber includes a furnace containing a fiber preform, a first positioner, a reheating device, and a treatment device downstream of the reheating device, the treatment device operable to cool the optical fiber under vacuum to reduce the rate of heat transfer from the optical fiber.

Abstract: A system for processing optical fiber includes a draw furnace, a fiber conveyance pathway extending between an upstream end positioned at the draw furnace and a downstream end positioned opposite the upstream end, where optical fiber is conveyed along the fiber conveyance pathway from the upstream end to the downstream end in a fiber conveyance direction, a muffle in communication with the draw furnace and positioned downstream of the draw furnace, a second cooling device annularly surrounding the fiber conveyance pathway downstream from the draw furnace, the second cooling device including one or more second cooling device heating elements and a first cooling device positioned between the draw furnace and the second cooling device, wherein the first cooling device directs a fluid to contact the optical fiber.

Abstract: A furnace system includes a muffle defining a furnace cavity. A lower heater is coupled to the muffle and is configured to create a hot zone within the furnace cavity having a temperature of about 1900° C. or greater. An upper muffle extension is positioned above the muffle and defines a handle cavity. A downfeed handle is positioned within the handle cavity such that a gap is defined between an outer surface of the downfeed handle and an inner surface of the upper muffle extension. An upper heater is thermally coupled to the upper muffle extension and configured to heat the gap. A gas screen is positioned in the upper muffle extension and is configured to inject a process gas into the handle cavity.

Abstract: An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle ?, wherein 2°???25°, and a cone height L1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d2, wherein 0.1 mm?d2?0.5 mm and a cylindrical height of L2, wherein 0.05 mm?L2?1.

Abstract: An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle ?, wherein 2°???25°, and a cone height L1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d2, wherein 0.1 mm?d2?0.5 mm and a cylindrical height of L2, wherein 0.05 mm?L2?1.

Abstract: A system and method for processing an optical fiber includes a treatment device disposed downstream of a furnace and including a treating zone. The treating zone includes a fiber inlet and fiber outlet and is configured to cool the optical fiber at a reduced pressure below ambient pressure and at a slow cooling rate less than an ambient cooling rate. A nozzle assembly is disposed at one or more of the fiber inlet, the fiber outlet, upstream of the treating zone, and downstream of the treating zone. The nozzle assembly includes multiple baffle plates defining a number of nozzle chambers, each nozzle chamber having a nozzle chamber pressure, wherein each baffle plate includes an orifice having a predetermined effective orifice diameter through which the optical fiber passes. Each nozzle chamber is configured to sequentially change a nozzle chamber pressure between the reduced pressure and ambient pressure.

Abstract: An apparatus for curing a coating composition disposed on a glass optical fiber. The apparatus includes a reflector, the reflector having an interior surface delineating a boundary of a cavity, the interior surface including a plurality of portions, each of the portions extending along a different curved contour. Furthermore, each of the plurality of portions is configured to reflect curing light so that the reflected curing light is concentrated to a curing zone within the cavity such that all the reflected curing light within the curing zone has an intensity of about 60% or greater relative to a maximum intensity of the reflected curing light. A fiber location for the glass optical fiber is located within the curing zone. Additionally, the plurality of portions includes at least a first portion and a second portion, the first portion having a different degree of curvature than the second portion.

Abstract: An optical fiber production system includes an annealing furnace having a furnace inlet, a furnace outlet, and a process tube extending between the furnace inlet and the furnace outlet, the process tube having a process tube wall and a heating zone including at least one heating element. The optical fiber production system also includes a gas distribution assembly fluidly coupled to the furnace outlet and structurally configured to induce gas flow from the gas distribution assembly into the process tube such that gas flows within the process tube in an upflow direction.

Abstract: A furnace system includes a muffle defining a furnace cavity. A lower heater is coupled to the muffle and is configured to create a hot zone within the furnace cavity having a temperature of about 1900° C. or greater. An upper muffle extension is positioned above the muffle and defines a handle cavity. A downfeed handle is positioned within the handle cavity such that a gap is defined between an outer surface of the downfeed handle and an inner surface of the upper muffle extension. An upper heater is thermally coupled to the upper muffle extension and configured to heat the gap. A gas screen is positioned in the upper muffle extension and is configured to inject a process gas into the handle cavity.

Abstract: Provided herein is a method of and system for processing an optical fiber. The method includes the steps of drawing an optical fiber in a drawing direction along a process pathway through a coating chamber comprising an inlet and an outlet, and a coating liquid volume to coat the optical fiber; supplying the coating liquid through the inlet, the coating liquid exiting the coating chamber through the outlet; and recirculating to coating liquid exiting the coating chamber to the inlet.

Abstract: A furnace system includes a muffle defining a furnace cavity. A lower heater is coupled to the muffle and is configured to create a hot zone within the furnace cavity having a temperature of about 1900° C. or greater. An upper muffle extension is positioned above the muffle and defines a handle cavity. A downfeed handle is positioned within the handle cavity such that a gap is defined between an outer surface of the downfeed handle and an inner surface of the upper muffle extension. An upper heater is thermally coupled to the upper muffle extension and configured to heat the gap. A gas screen is positioned in the upper muffle extension and is configured to inject a process gas into the handle cavity.

Abstract: An optical fiber forming apparatus comprises: a draw furnace comprising: (i) a muffle with an inner surface, (ii) an axial opening below the muffle, the inner surface of the muffle defining a passageway extending through the axial opening, and (iii) an upper inlet into the passageway; and a tube that extends into the passageway of the draw furnace above the axial opening, the tube having (i) an outer surface and the inner surface of the muffle surrounds the outer surface of the tube with a space separating the outer surface of the tube from the inner surface of the muffle, (ii) an inner surface that defines a second passageway extending through the tube, (iii) an inlet into the second passageway of the tube, (iii) an outlet out of the second passageway of the tube.

Abstract: A method of processing an optical fiber includes drawing the optical fiber from a heated glass source, reheating the optical fiber, and cooling the optical fiber under vacuum at a cooling rate less than the cooling rate of the optical fiber in air at 25° C. and 1 atm. Cooling the optical fiber under vacuum is conducted after reheating the optical fiber. Cooling the optical fiber under vacuum reduces the rate of heat transfer from the optical fiber, which may enable further relaxation of the glass and reduction in the fictive temperature of the optical fiber. A system for processing an optical fiber includes a furnace containing a fiber preform, a first positioner, a reheating device, and a treatment device downstream of the reheating device, the treatment device operable to cool the optical fiber under vacuum to reduce the rate of heat transfer from the optical fiber.

Abstract: Optical fibers having low fictive temperature and methods of making such fibers are described. Management of the cooling rate of an optical fiber during fiber draw permits control over the fictive temperature of the fiber. Non-monotonic cooling rates are shown to promote reductions in fiber fictive temperature. The non-monotonic cooling includes slower cooling rates in upstream portions of the process pathway and faster cooling rates in downstream portions of the process pathway. Reduction in fiber fictive temperature is achieved by controlling the ambient temperature of the fiber to slow the cooling rate of the fiber in upstream portions of the process pathway that correspond to the fiber temperature regime in which the fiber viscosity is sufficiently low to permit efficient structural relaxation. Increases in cooling rate in downstream portions of the process pathway permit adjustment of fiber temperature as needed to meet entrance temperature requirements of downstream processing units.

Abstract: A method of processing an optical fiber includes drawing the optical fiber from a heated glass source, reheating the optical fiber, and cooling the optical fiber under vacuum at a cooling rate less than the cooling rate of the optical fiber in air at 25° C. and 1 atm. Cooling the optical fiber under vacuum is conducted after reheating the optical fiber. Cooling the optical fiber under vacuum reduces the rate of heat transfer from the optical fiber, which may enable further relaxation of the glass and reduction in the fictive temperature of the optical fiber. A system for processing an optical fiber includes a furnace containing a fiber preform, a first positioner, a reheating device, and a treatment device downstream of the reheating device, the treatment device operable to cool the optical fiber under vacuum to reduce the rate of heat transfer from the optical fiber.

Abstract: A system for processing optical fiber includes a draw furnace, a fiber conveyance pathway extending between an upstream end positioned at the draw furnace and a downstream end positioned opposite the upstream end, where optical fiber is conveyed along the fiber conveyance pathway from the upstream end to the downstream end in a fiber conveyance direction, a muffle in communication with the draw furnace and positioned downstream of the draw furnace, a second cooling device annularly surrounding the fiber conveyance pathway downstream from the draw furnace, the second cooling device including one or more second cooling device heating elements and a first cooling device positioned between the draw furnace and the second cooling device, wherein the first cooling device directs a fluid to contact the optical fiber.

Abstract: Optical fibers having low fictive temperature and methods of making such fibers are described. Management of the cooling rate of an optical fiber during fiber draw permits control over the fictive temperature of the fiber. Non-monotonic cooling rates are shown to promote reductions in fiber fictive temperature. The non-monotonic cooling includes slower cooling rates in upstream portions of the process pathway and faster cooling rates in downstream portions of the process pathway. Reduction in fiber fictive temperature is achieved by controlling the ambient temperature of the fiber to slow the cooling rate of the fiber in upstream portions of the process pathway that correspond to the fiber temperature regime in which the fiber viscosity is sufficiently low to permit efficient structural relaxation. Increases in cooling rate in downstream portions of the process pathway permit adjustment of fiber temperature as needed to meet entrance temperature requirements of downstream processing units.

Abstract: An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle ?, wherein 2°???25°, and a cone height L1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d2, wherein 0.1 mm?d2?0.5 mm and a cylindrical height of L2, wherein 0.05 mm?L2?1.

Abstract: An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle ?, wherein 2°???25°, and a cone height L1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d2, wherein 0.1 mm?d2?0.5 mm and a cylindrical height of L2, wherein 0.05 mm?L2?1.