Fitel USA Corporation

Lucent Technologies Inc.

Ofs Fitel, LLC

Furukawa Electric Na

Thomas Edward Stockert

John Burnette MacChesney

Yoram De Hazan

Suhas Dattatreya Bhandarkar

Man Fei Yan

David Wilfred Johnson

Patrick William Wisk

George J Shevchuk

Robert Scott Windeler

Debra Anne Fleming

Christopher Alan White

Gardy Cadet

Dennis J Trevor

Frederick W Walz, Jr

Victor M Lubecke

Eric M Monberg

Philip J Hubbauer

Jeffrey Linn Bream

Philip Habbauer

The specification describes the production of optical fibers and optical fiber preforms using Chemical Powder Deposition (CPD). In this process a slurry of silica powders and dopant powders in a liquid carrier is prepared and the inside surface of a silica glass starter tube is coated with the slurry, then dried. The coating is then consolidated and the tube collapsed as in the conventional MCVD process. Multiple coatings, and coatings with varying compositions, can be used to produce any desired profile. In an alternative embodiment, doped silica glass of the desired final composition is prepared, and then pulverized to form the powder for the slurry. In both embodiments, the use of powders of known composition in the slurry allows direct control over the final glass composition, as compared with conventional processes in which the composition in the final glass is indirectly controlled by control of the thermodynamics of a vapor phase reaction.

Chemical powder deposition method for the manufacture of optical fiber preforms and optical fibers

The use of large dense vitreous spherical (LDVS) silica powders for making sol-gel silica bodies has been found to have important advantages. Among these are higher gel strength, higher silica loading, more rapid aging and drying of the gel, a reduction in the amount of organic additives leading to reduced process time required for organic burn-off, and easier removal of contaminant particles due to their larger size. It was also discovered that combining LDVS particles with conventional non-spherical, lower density, aggregate particle mixtures, further improves the process.

Manufacture of silica bodies using sol-gel techniques

The doped silica core region of a core rod for an optical fiber preform is protected against unwanted fluorine doping during fluorine doping of the outer silica layer by selectively consolidating the core region prior to fluorine doping. Due to dopants in the core region, the soot in the core region consolidates before the soot in the outer undoped region. This inherent property allows the entire core rod to be heated prior to fluorine doping resulting in selective partial consolidation and preventing fluorine doping of the doped center core region. The process time required may be reduced by using incremental fluorine doping. In the incremental doping process the doping step is separated into a deposit step, where &ldquo;excess&rdquo; fluorine is deposited on the silica particles, and a drive-in step where atomic fluorine is distributed into the silica particles. The drive-in step is conveniently combined with the sintering or consolidation step to further enhance the efficiency of the doping process.

Controlled collapse of depressed index optical fiber preforms

Optical fiber design for secure tap proof transmission

Silica structure crack monitoring

The process time required for fluorine doping of porous silica bodies to produce fluorine doped preforms for the manufacture of depressed index optical fibers is reduced by separating the doping step into a predeposit step, where &ldquo;excess&rdquo; fluorine is deposited on the silica particles, and a drive-in step where atomic fluorine is distributed into the silica particles. The drive-in step is conveniently combined with the sintering or consolidation step to further enhance the efficiency of the doping process.

Manufacture of depressed index optical fibers

The use of silica powders having large particle sizes in making sol-gel silica bodies has been found to have important advantages. Among these are higher gel strength, higher silica loading, more rapid aging and drying of the gel, a reduction in the amount of organic additives leading to reduced process time required for organic burn-off, and easier removal of contaminant particles due to their larger size. It was also discovered that spherical particle morphology contributes to the improved properties.

A tube take-up apparatus is provided to handle a length of freshly extruded tube. The apparatus includes an elongated housing in which a pair of parallel, spaced-apart rollers extend lengthwise in a position just below the extruded tubing. The housing is removably mounted on an elongated supporting fin which is secured to the extruder at its near end, extends upwardly between the two rollers and substantially along the entire length of the housing, and is, in turn, supported on a fixed pedestal at its remote end. After the full length of tubing has been extruded, the housing and rollers as a unit are lifted with the tube from the supporting fin and replaced by an empty housing, to extrude the next tube, while the full housing is carried away to a dryer.

Apparatus and method for handling extruded tubes

The disclosed method of making microstructured optical fiber comprises providing a mold, with a multiplicity of elongate elements extending into the mold and being maintained in a predetermined spatial arrangement with respect to the mold. Silica-containing sol is introduced into the mold and is caused to or permitted to gel, such that a gel body results. After removing the elongate elements from the gel body and removing the gel body from the mold, the gel body is dried, sintered and purified, and the microstructured fiber is drawn from the sintered body.

Sol gel method of making an optical fiber with multiple apetures

A silica-water dispersion suitable for use as a sol for sol-gel fabrication is produced from a silica-water mixture with addition of alkaline agent. The agent functions to increase viscosity so as to improve dispersing efficiency during shear mixing.

Process entailing sol-gel production of silica glass

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.

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Millburn, NJ, United States of America

Thomas Edward Stockert