Lucent Technologies Inc.

Ofs Fitel, LLC

At&t Bell Laboratories

Other

Fitel USA Corporation

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

Agere Systems Guardian Corp.

Furakawa Electric North America, Inc.

Furukawa Electric North America, Inc.

James William Fleming

George J Zydzik

Man Fei Yan

Fred P Partus

Robert M Atkins

Paul Francis Glodis

Robert M Pafchek

Adolph H Moesle, Jr

Allan James Bruce

Kenneth L Walker

John Burnette MacChesney

Jeffrey W Nicholson

John Michael Fini

David W Johnson, Jr

Gordon Albert Thomas

Thierry Franck Taunay

Jinkee Kim

David Kalish

Thomas John Miller

George Edward Oulundsen, Iii

Ryan Bise

Robert L Lingle

Richard G Huff

Siu-Ping Hong

Frank Vincent DiMarcello

Durgesh Vaidya

Zhi Zhou

Eric M Monberg

Arthur Clifford Hart, Jr

Roman Shubochkin

Karen S Kranz

Kasyapa Balemarthy

Richard M Lum

Matthijs M Broer

Shunhe Xiong

Sandra A Pardenek

John C Alonzo

David D Braganza

Michael L Pearsall

Jerry R Bautista

Merrill H Brodeur

Sandeep Kakar

Thierry F Taunay

Described is a technique for the design and manufacture of MMFs. Designs are implemented so as to limit the maximum variation in z(r, &#x3bb;) with respect to wavelength, where z(r, &#x3bb;) is the dielectric constant weighted by the square of the wavelength. MMFs for use in CWDM applications are specifically described.

Manufacture of multi-mode optical fibers

An optical fiber includes a core region having a longitudinal axis. A cladding region surrounds the core region. The core region and cladding region are configured to support and guide the propagation of signal light in a fundamental transverse mode in the core region in the directions of the axis. The fiber has a bend-induced gradient of its equivalent index of refraction indicative of a loss in guidance of the mode. At least a portion of cladding region has a graded index of refraction opposite the bend-induced gradient. The cladding region is configured to have a substantially flat equivalent index in response to a bend of the optical fiber.

Bend compensated filter fiber

The specification describes multimode optical fibers produced by improved methods that reduce the manufacturing cost. These methods may also be more efficient in terms of power loss. In one of the embodiments, the improved design has a large core of pure silica derived from a rod-in-tube method. In the embodiment, a down-doped cladding is produced by depositing fluorine-doped silica on the inside of a silica starting tube using isothermal radio frequency plasma deposition. The silica core is inserted and the starting tube collapsed. The silica starting tube is removed and optical fiber is drawn from the fluorine-doped glass coated silica rod.

Large core multimode optical fibers

An isothermal, low pressure-based process of depositing material within a substrate has been developed and results in creating an extremely narrow reaction zone within which a more uniform and efficient deposition will occur. Sets of isothermal plasma operating conditions have been found that create a narrow deposition zone, assuring that the deposited material is clear glass rather than soot particles. The chemical delivery system, in one arrangement, utilizes rods of solid phase source material (which may otherwise be difficult to obtain in gaseous form). The operating conditions are selected such that the hot plasma does not transfer a substantial amount of heat to the substrate tube, where the presence of such heat has been found to result in vaporizing the reactant material (creating soot) and developing hot spots.

Method of fabricating optical fiber using an isothermal, low pressure plasma deposition technique

An isothermal, low pressure-based process of depositing material within a substrate has been developed, and is particularly useful in forming an optical fiber preform results in creating an extremely narrow reaction zone within which a more uniform and efficient deposition will occur. Sets of isothermal plasma operating conditions have been found that create a narrow deposition zone, assuring that the deposited material is clear glass rather than soot particles. The exhaust end of the tube is connected to a vacuum system which is in turn connected to a scrubber apparatus for removal and neutralization of reaction by-products. The operating conditions are selected such that the hot plasma does not transfer a substantial amount of heat to the substrate tube, where the presence of such heat has been found to result in vaporizing the reactant material (creating soot) and developing hot spots.

The specification describes methods for the manufacture of very large optical fiber preforms wherein the core material is produced by MCVD. Previous limitations on preform size inherent in having the MCVD starting tube as part of the preform process are eliminated by removing the MCVD starting tube material from the collapsed MCVD rod by etching or mechanical grinding. Doped overcladding tubes are used to provide the outer segments of the refractive index profile thus making most effective use of the MCVD produced glass and allowing the production of significantly larger MCVD preforms than previously possible.

MCVD optical fiber method with partial removal of substrate tube

Methods for modifying preform core ovality during and subsequent to the formation of an optical fiber preform. After MCVD deposition forms the core rod, but prior to overcladding of the core rod, the code rod may be etched to change its ovality. In order to etch the core rod, the core rod may be mounted to lathe, rotated by at least two rotors, and subjected to a heat source. Additionally, one of the at least two rotors may be phase-shifted from another one of the at least two rotors after the core rod is mounted on the lathe.

Methods for modifying ovality of optical fiber preforms

An optical fiber preform comprising a plurality of longitudinal air holes is subjected to a thermal treatment (i.e., heating), coupled with the application of a compressive force on either end of the heated preform to compress the entire preform structure a predetermined amount. The thermal compression treatment has been found to smooth any roughened glass surfaces and heal microcracks that may have formed during the preform fabrication process, essentially 'knitting' the glass material back together and forming a preform of improved quality over the prior art microstructured preforms.

Optical fiber preform with improved air/glass interface structure

A silicate optical fiber comprises a graded index silicate core co-doped with aluminum oxide, phosphorus oxide, germanium oxide and fluorine in unique compositions that we have discovered allow multimode, multi-wavelength operation without significant intermodal dispersion. Illustratively, the core comprises a multiplicity of compositions whose refractive indices are graded from a maximum at or near the center of the core to a minimum at the interface with the cladding. Each core composition resides within a sub-volume of a 5 dimensional phase space in which an optimum core profile shape is essentially constant over the wavelength range of operation of the fiber. For operation in the wavelength range of about 0.78 &#x3bc;m to 1.55 &#x3bc;m, each composition preferably comprises no more than approximately 6 mole % AlO, 9 mole % PO, 6 mole % GeO, 6 mole % F, and 90-100 mole % SiO.

Multi-wavelength, multimode optical fibers

A silica-based core rod is traversed by a heat source along its longitudinal axis, to provide heated, softened regions. During the traverse, compressive or tensile movements are provided along the rod's longitudinal axis, these movements inducing, respectively, increases or decreases in the core diameter at the softened regions. By providing selective core diameter increases and/or decreases across the entire length of the core rod, a desired core diameter profile is attained. It is possible to attain a substantially uniform core diameter, or a varying core diameter profile that provides particular properties, such as systematically varying dispersion. In addition, due to the ability to increase core diameter and core rod diameter in a controlled manner, it is possible to make larger core rods, and in turn larger fiber preforms, than presently possible.

Process for fabricating optical fiber involving tuning of core diameter profile

An improved technique for assembling and drawing fiber from preforms is provided. In one embodiment, the technique involves providing a core rod assembly comprising a core rod and a bushing attached at an end of the assembly. The core rod assembly is inserted into an unsintered overcladding tube, and secured to the tube such that the core rod assembly is suspended within. The overcladding tube and the core rod assembly are heated to sinter the overcladding tube and thereby form a preform assembly. During the heating step, the bushing comes into contact with the interior of the overcladding tube, and, because the bushing has a larger diameter than the core rod, an annular gap is maintained between the core rod assembly and the interior of the overcladding tube. It is then possible to attach a draw handle to the preform assembly, place the preform assembly into a draw tower, and draw fiber from the preform assembly by an overclad during draw technique.

Process for fabricating optical fiber involving overcladding during sintering

An improved process for fabricating a refractory dielectric article, in particular silica optical fiber, is provided. The fabrication process involves joining of two elongated bodies&mdash;typically silica preforms&mdash;end-to-end by use of an isothermal plasma torch technique. A long preform made in this manner allows drawing of optical fiber with less down-time and waste than current processes. The plasma torch technique also produces low perturbations within the resultant preform, thereby increasing the amount of usable fiber.

Process for fabricating silica article involving joining of discrete bodies

The smoothness of refractory dielectric bodies, particularly silica sol-gel bodies, is substantially improved by a relatively straightforward treatment. In particular, the surface of the body is treated with a plasma fireball, such as induced by a plasma torch. The treatment is able to reduce the roughness, as measured by RA, in overcladding tubes formed by a sol-gel process by at least a factor of 2, typically at least a factor of 5. It is also possible to improve the smoothness of silica tubes that are drawn from a billet. Typically, the process reduces the roughness of silica bodies to an RA of about 1 microinch or less.

Process for fabricating article comprising refractory dielectric body

A refractory dielectric body is heated with a plasma fireball at conditions which do not result in substantial removal of a surface portion of the body, yet which are sufficient to reduce both surface and bulk impurities. Typically, the body is treated with the plasma in the absence of simultaneous deposition of material onto the body. Advantageously, an isothermal, oxygen or oxygen-containing plasma is utilized. The invention is useful for reducing chlorine impurities by at least about 30% to a depth of at least about 10 .mu.m, with accompanying reduction of hydroxyl impurities. The invention thus provides a useful method for reducing the concentration of impurities that contribute to imperfections during the process of drawing fiber from an optical fiber preform, without requiring substantial removal of the surface of the preform.

Method for manufacturing an article comprising a refractory a dielectric

A refractory dielectric body is heated with a plasma torch at conditions which do not result in substantial removal of a surface portion of the body, yet which are sufficient to reduce both surface and bulk impurities. Typically, the body is solid, e.g., a rod as opposed to a tube, and is treated with the plasma in the absence of simultaneous deposition of material onto the body. Advantageously, an isothermal plasma torch is utilized, and the torch advantageously produces an oxygen or oxygen-containing plasma. The invention is useful for reducing chlorine impurities by at least about 30% to a depth of at least about 10 .mu.m, with accompanying reduction of hydroxyl impurities. The invention thus provides a useful method for reducing the concentration of impurities that contribute to imperfections during the process of drawing fiber from an optical fiber preform, without requiring substantial removal of the surface of the preform.

Method for manufacturing an article comprising a refractory dielectric

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Westfield, NJ, United States of America

James William Fleming