Lucent Technologies Inc.

At&t Bell Laboratories

Furukawa Electric North America, Inc.

Bell Telephone Laboratories

Ofs Fitel, LLC

Frank Vincent DiMarcello

Richard G Huff

Karen S Kranz

David John DiGiovanni

Kenneth L Walker

George Edward Oulundsen, Iii

Xinli Jiang

Arthur C Hart

Sandeep Prabhakar Pandit

James William Fleming

Paul Joseph Lemaire

Lee L Blyler

Arthur Clifford Hart, Jr

Frederick W Walz, Jr

Lisa M Larsen-Moss

John Charles Williams

Richard Garner Huff

George E Oulundsen

Danid John Digiovanni

The specification describes a technique for drawing circular core multimode optical fiber using twist during draw to increase fiber bandwidth.

Multimode optical fibers with increased bandwidth

Method of impressing a twist on a multimode fiber during drawing

A method and apparatus for high velocity dual coating optical fibers includes passing the fiber to be coated through an entrance die into a coating reservoir, to which liquid coating material is supplied under pressure. The diameter of the die passage and the pressure of the fluid is sufficient to prevent air from entering the reservoir. The coated fiber is passed through a centering and sizing die wherein the recirculation of excess coating material is controlled to produce centering forces on the fiber at the high fiber velocity, and wherein the initial coating is sized. The fiber is then passed through a second coating reservoir into an exit die which sizes the second coating. Upon leaving the exit die, the coatings are cured.

Biconic coating die for making coated optical fibers

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

A fiber drawing apparatus is provided with an improved fiber draw furnace wherein an inner zirconia tube is surrounded by a radially-spaced annular insulating region of magnesia within a silica beaker. While the magnesia has a melting point approximately the same as zirconia, the electrical conductivity of magnesia is substantially lower, enabling it to withstand higher RF power. Moreover magnesia is more soluble than zirconia in silica, reducing the likelihood of particulate contamination of the fiber.

Magnesia fiber draw furnace

This invention is a process of contactless monitoring the tension in a moving fiber, such as during the process of drawing optical fibers from preforms, and a non-contacting tension gauge which allows measurement of fiber tension at line speed. The device can be used to monitor the tension during the run without any adverse effects on fiber performance. The measurement may be steady, intermittent or sinusoidal as appropriate. The process includes the steps of sensing an initial position of a moving optical fiber, applying a gas jet onto a section of the optical fiber in a direction transverse to the direction of movement of the fiber so as to cause deflection of the moving fiber axially of the gas jet, sensing the magnitude of deflection of the fiber relative to the said initial position, and, depending on the magnitude of deflection, adjusting the tension in the fiber so as to cause the change in the magnitude of deflection to a preselected value. The monitoring is especially suitable for monitoring the tension in an optical fiber being drawn from a heated preform, the tension being adjusted by adjusting the temperature of the fiber-drawing furnace.

Method and apparatus for contactless monitoring of tension in a moving

A hermetically coated optical fiber is produced by contacting a hot fiber with an organic material such as acetylene. The heat of the fiber causes decomposition and results in a hermetic, carbonaceous coating. This coating is essentially impermeable to both water and hydrogen.

Hermetically sealed optical fibers

Optical fibers having ultraviolet-cured coatings and reduced optical transmission losses are produced. An ultraviolet-absorbing material is incorporated in at least one coating layer. This reduces damage in the glass fiber due to the ultraviolet-curing radiation, while still allowing rapid curing of the coating. Single layer coatings and dual layer coatings are described. A single layer coating having reduced microbending losses due to partial curing of the inner portion of the coating is also described.

Ultraviolet absorbers in optical fiber coatings

A graded index optical fiber with a structure which results in improved pulse dispersion characteristics is disclosed. The refractive index properties of the fiber core may be defined in terms of coaxially nested tubular regions, each of different index of refraction, which together form a radially graded index of refraction. The optical properties of each tubular region vary periodically along the longitudinal direction. The longitudinal variation of each tubular region is in approximate antiphase with the longitudinal variation of the tubular regions immediately adjacent to it. In the disclosed structure each tubular region is composed of at least two intertwined helical ribbons of material.

Graded index optical fiber

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Annandale, NJ, United States of America

Frank Vincent DiMarcello