Lucent Technologies Inc.

At+t Corp.

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Agere Systems Guardian Corp.

Frederick W Walz, Jr

John Burnette MacChesney

Debra Anne Fleming

David W Johnson, Jr

Edwin Arthur Chandross

David Wilfred Johnson

Thomas Edward Stockert

Frank Vincent DiMarcello

Eric M Monberg

Philip J Hubbauer

Karen S Kranz

Richard Garner Huff

The invention involves fabricating a ceramic tube, e.g., a silica overcladding tube, with very little bow, e.g., about 0.3 mm per meter or less. In particular, the invention involves securing the tube by a handle that both allows the tube to hang plumb during treatment, and also is capable of deforming during such heat treatment to maintain the plumb arrangement.

Process of sintering a hanging silica tube so as to exhibit a low bow

The invention is a sol-gel extrusion process which allows fabrication of both thick and thin wall tubes. For example, the process is capable of preparing silica overcladding tubes in a manner easier than sol-gel casting processes, and also capable of preparing relatively thin substrate tubes, which are difficult to cast. According to the invention, a silica dispersion containing a stabilizing agent is provided, a gelling agent is added to the dispersion to induce gellation, and the resultant gel is extruded into a silica body, in the substantial absence of polymeric material from the gel. Substantially avoiding the inclusion of such polymeric material in overcladding and substrate tubes offers significant commercial advantages by reducing the time and energy required to remove organic materials from the tube bodies, by reducing environmental impact, and by reducing the amount of impurities introduced in the tubes.

Process for fabricating silica article utilizing sol-gel extrusion

Fiber bow makes mass fusion splicing of optical fiber difficult and this is undesirable. We have found that fiber bow can be significantly reduced if the fiber that is being drawn from a heated optical fiber preform is caused to run through a tubular cooling chamber that extends from the draw furnace, the cooling chamber comprising a tube of inner diameter d.sub.1 &lt;35 mm, preferably &lt;20 mm. In a preferred embodiment the cooling chamber includes an upper cooling chamber of inner diameter d.sub.2 &gt;d.sub.1, with a transition element providing a smooth transition between the two chambers. The cooling chamber desirably is free of turbulence-causing air leaks and/or geometrical features.

Method of making optical fiber

Lowered cost fabrication including preparation of large bodies of void-free, high-silica glass, depends upon gellation of an aqueous sol of colloidal silica particles, followed by drying and firing of such gel. Freedom from cracks in the dried gel is the consequence of included polymeric material which wets the particles. The polymeric material is removed by thermal decomposition attended upon temperature attained in firing.

Vitreous silica product manufactured via a sol-gel process using a

Manufacture of vitreous silica product via a sol-gel process using a

The disclosed method of producing optical fiber comprises providing a silica-based glass rod of diameter D that comprises a core region of effective diameter d surrounded by cladding material (D/d typcially&gt;2) and a silica-based porous jacketing tube, inserting the glass core rod into the porous tube, consolidating the porous material and sintering the jacketing tube onto the core rod such that a substantially pore-free optical fiber preform results. Fiber is then drawn from the preform in the conventional manner. Consolidation and sintering is carried out at a temperature below the softening temperature of the material, typically &lt;1600.degree. C. In a preferred embodiment, the porous tube is produced by a sol/gel process that comprises mixing colloidal silica (surface area 5-100 m.sup.2 /g) and water, adding quaternary ammonium hydroxide to the sol such that a pH in the range 11-14 results, lowering the pH into the range 4-11 by addition of methyl or ethyl formate, casting the sol into an appropriate mold and permitting it to gel. The relatively low processing temperature is an advantageous feature of the inventive process that, inter alia, makes it easier to maintain the fiber core concentric with the cladding.

Method of producing an optical fiber

Growing community of inventors

Plainfield, NJ, United States of America

Frederick W Walz, Jr