Abstract: Disclosed is an optical fiber having a core with an alkali metal oxide dopant in an peak amount greater than about 0.002 wt. % and less than about 0.1 wt. %. The alkali metal oxide concentration varies with a radius of the optical fiber. By appropriately selecting the concentration of alkali metal oxide dopant in the core and the cladding, a low loss optical fiber may be obtained. Also disclosed are several methods of making the optical fiber including the steps of forming an alkali metal oxide-doped rod, and adding additional glass to form a draw perform. Preferably, the draw preform has a final outer dimension (d2), wherein an outer dimension (d1) of the rod is less than or equal to 0.06 times the final outer dimension (d2). In a preferred embodiment, the alkali metal oxide-doped rod is inserted into the centerline hole of a preform to form an assembly.

Abstract: A method of manufacturing an optical waveguide preform includes providing a first process gas atmosphere to a soot preform contained in a vessel. The first atmosphere is held in the vessel for a first reacting time sufficient to at least partially dope or dry the soot preform. The vessel is then at least partially refilled with a second doping or drying atmosphere. The second doping or drying atmosphere is held in the vessel for a second reacting time sufficient to further dope or dry the soot preform.

Abstract: The present invention relates to a process for manufacturing flat sheets of a glass-based material and to an apparatus therefor. The process comprises providing a glass preform, heating the glass preform in a furnace, forming a gob and a pre-sheet, removing the gob and drawing the glass pre-sheet into a flat glass sheet. Also provided is an apparatus for drawing a glass preform into a glass sheet, the apparatus comprising a draw furnace, stretching arms for stretching and drawing the pre-sheet into a glass sheet, and opposing edge rollers for applying a downward force on the glass sheet. The draw furnace may include a plurality of individual heating elements, the temperature of each heating element capable of being separately controlled. The apparatus may further include an annealing furnace for annealing the glass sheet.

Abstract: The present invention relates to a process for manufacturing flat sheets of a glass-based material and to an apparatus therefor. The process comprises providing a glass preform, heating the glass preform in a furnace, forming a gob and a pre-sheet, removing the gob and drawing the glass pre-sheet into a flat glass sheet. Also provided is an apparatus for drawing a glass preform into a glass sheet, the apparatus comprising a draw furnace, stretching arms for stretching and drawing the pre-sheet into a glass sheet, and opposing edge rollers for applying a downward force on the glass sheet. The draw furnace may include a plurality of individual heating elements, the temperature of each heating element capable of being separately controlled. The apparatus may further include an annealing furnace for annealing the glass sheet.

Abstract: An optical fiber is disclosed in which the core region of the optical fiber is doped with Cl and F in order to reduce the viscosity mismatch between the core region and the adjacent cladding region. In one embodiment of the invention, the optical fiber is a single-mode step index optical fiber having a core region doped with Cl and F in an amount effective to produce a difference in temperature between the glass transition temperature of the core region and the glass transition temperature of the adjacent cladding region of less than about 200° C.

Abstract: A method of making an optical waveguide preform includes forming a preform including a first portion and a second radial portion, wherein the second portion includes a dopant, and wherein the first portion exhibits a density greater than the second portion. The method further includes stripping at least a portion of the dopant from the second portion. In a preferred embodiment, the stripped dopant has migrated in a previous processing step.

Abstract: An optical fiber is disclosed in which the core region of the optical fiber is doped with Cl and F in order to reduce the viscosity mismatch between the core region and the adjacent cladding region. In one embodiment of the invention, the optical fiber is a single-mode step index optical fiber having a core region doped with Cl and F in an amount effective to produce a difference in temperature between the glass transition temperature of the core region and the glass transition temperature of the adjacent cladding region of less than about 200° C.

Abstract: The invention includes a method of incorporating fluorine into a preform that may be used to produce an optical article. A method that may be used to practice the invention includes a method of making an optical fiber preform. The method includes reacting a fluorine containing precursor in a flame of a combustion burner without forming a soot, thereby forming a fluorine doping atmosphere. A further method that may be practiced to practice the invention includes the step reacting at least a fluorine containing precursor in a flame of a combustion burner, wherein the precursors reacted in the flame are substantially devoid of the element of silicon, thereby forming a fluorine containing atmosphere for the doping of a soot preform.

Abstract: A method of manufacturing a cane suitable for forming an optical fiber, and a method of forming an optical fiber from the cane. A core composition having about 20% to 30% by weight of P2O5 is formed. An inner cladding composition is formed on an outer surface of the core composition and the core composition and the inner cladding composition are consolidated into a preform having a core and an inner cladding while substantially closing a center line hole of the preform. An outer cladding composition is formed on the preform to define a cane. The cane can then be transformed into an optical fiber.

Abstract: The invention includes a method of incorporating fluorine into a preform that may be used to produce an optical article. A method that may be used to practice the invention includes a method of making an optical fiber preform. The method includes reacting a fluorine containing precursor in a flame of a combustion burner without forming a soot, thereby forming a fluorine doping atmosphere. A further method that may be practiced to practice the invention includes the step reacting at least a fluorine containing precursor in a flame of a combustion burner, wherein the precursors reacted in the flame are substantially devoid of the element of silicon, thereby forming a fluorine containing atmosphere for the doping of a soot preform.

Abstract: A method of manufacturing an optical waveguide preform includes providing a first process gas atmosphere to a soot preform contained in a vessel. The first atmosphere is held in the vessel for a first reacting time sufficient to at least partially dope or dry the soot preform. The vessel is then at least partially refilled with a second doping or drying atmosphere. The second doping or drying atmosphere is held in the vessel for a second reacting time sufficient to further dope or dry the soot preform.

Abstract: A method of making an optical waveguide preform includes forming a preform including a first portion and a second radial portion, wherein the second portion includes a dopant, and wherein the first portion exhibits a density greater than the second portion. The method further includes stripping at least a portion of the dopant from the second portion. In a preferred embodiment, the stripped dopant has migrated in a previous processing step.

Abstract: A method of making a phosphosilicate fiber comprises the steps of: (i) manufacturing a preform containing phosphorus doped silica; and (ii) drawing phosphosilicate fiber from said preform at a temperature in the range of 1700° C. to 1900° C.

Abstract: The disclosed invention includes an inventive drying agent. The drying agent includes at least one halide and at least one reducing agent. Preferably, the reducing agent includes a compound that will react with an oxygen by-product of the reaction of the halide and water, or the reaction of the halide and an impurity in the preform. The invention also includes a method of drying a soot preform. The method includes disposing the soot preform in a furnace. The furnace is charged with the drying agent which includes the halide and the reducing agent. Heat is then supplied to the furnace. Suitable drying agents for use in the disclosed invention include a mixture of Cl2 and CO; a mixture of Cl2, CO and CO2; and POCl3.