Lucent Technologies Inc.

Agere Systems Guardian Corp.

American Telephone and Telegraph, Co.

Fitel USA Corporation

Eric M Monberg

David Anton Mixon

Richard M Lum

John Burnette MacChesney

James William Fleming

Thomas Edward Stockert

Dennis J Trevor

Frederick W Walz, Jr

Yoram De Hazan

Jim E Chemans

Sandeep Kakar

Lisa Carol Green

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

A process produces a glass overcladding tube from a silica gel body. The process includes passing the gel body through a hot zone under conditions that cause partial sintering of the gel body and repassing the gel body through the hot zone under conditions that further sinter the gel body into a glass overcladding tube.

Multi-pass sintering of a sol-gel body through a hot zone

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

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

A process deals with gaseous by-products and tarry materials during formation of sol-gel bodies. Gaseous products from a dehydroxylation reactor pass into a gas-fluid contactor. During the early stages of heat treatment, an aqueous acid solution is recirculated through the contactor to trap basic and/or water soluble organic gaseous materials. The resultant solution and non-condensing gases pass into a reservoir. Volatile, undissolved organics exit from the reservoir with non-condensing reactor gases and are treated. Once the organics have burned out of the sol-gel body, recirculation of the aqueous acid solution is ceased, and the gas-fluid contactor is flushed. The water flow is then ceased and dry nitrogen is provided to the contactor. During the next stage of the sol-gel heat treatment, gaseous products from the dehydroxylation reactor pass through the contactor into the caustic scrubber. Once the heat treatment is complete, the contactor is flushed.

Process and apparatus for treating gaseous products of sol-gel manufacturing

In a vertical gradient freeze (VGF) process for growing a large crystal of a Group III-V compound semiconductor in a pyrolytic boron nitride crucible (11), a major part of the inner surface of the crucible is first oxidized to form a boric oxide layer (12).

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Princeton, NJ, United States of America

Eric M Monberg