Fitel USA Corporation

At&t Bell Laboratories

Other

At&t Technologies, Inc.

Lucent Technologies Inc.

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

Thomas John Miller

David Kalish

Douglas W Monroe

Kai H Chang

Siu-Ping Hong

David A Nicol

Don H Smith

Shunhe Xiong

David B Steele

James William Fleming

Paul Francis Glodis

Zhi Zhou

Joseph P Fletcher, Iii

Anthony T D'Annessa

Franz T Geyling

William M Flegal

Xiaoyuan Dong

Michael L Pearsall

Andrew W Jones

Jerry W Baumgart

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

A three-dimensional reactionary turkey target includes a target stand shaped to represent the body of a turkey and a reactionary head and neck target that is shaped to represent the vital region of a turkey's head and neck. The head and neck target connects to the target stand, which is held in position via a support means. The target allows youth, novice, and experienced turkey hunters to assess the pattern of a turkey gun, gauge the shooter's accuracy, determine the efficacy of ammunition, and practice with a life-like target.

Three-dimensional reactionary turkey target

Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.

Method for fabricating optical fiber using deuterium exposure

Embodiments of the invention include an optical fiber preform assembly and a method for making optical fiber using the preform assembly. The assembly includes a preform core rod, at least one overclad tube formed around the preform core rod, a handle attached to one end of the overclad tube, and a refractory material positioned in the overclad tube between the preform core rod and the handle. The refractory material reduces if not prevents movement of the preform core rod into the handle during the fiber draw process. Preferably, the refractory material is made of, e.g., magnesium oxide and/or aluminum oxide, and has a melting point, e.g., greater than approximately 2000 degrees Celsius. Embodiments of the invention also include a method for making optical fiber using this preform assembly.

Rod-In-Tube optical fiber preform assembly and method having reduced movement

Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. The method includes the steps of dehydrating an optical fiber glass core rod in a first environment including oxygen and at least one of chlorine-containing gases, fluorine-containing gases and carbon monoxide; and adjusting the oxygen stoichiometry of the first environment so that it is neither oxygen-rich nor oxygen-deficient. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.

Method of making an optical fiber using preform dehydration in an environment of chlorine-containing gas, fluorine-containing gases and carbon monoxide

Embodiments of the invention include a method and apparatus for making a multiple overclad optical fiber preform. The method includes positioning a first overclad tube around a preform core rod, positioning at least one second overclad tube around the first overclad tube, and collectively heating the preform core and the overclad tubes under pressure to collapse the overclad tubes onto the preform core rod thus producing a multiple overclad optical fiber preform. The apparatus includes a preform core rod, a first overclad tube surrounding the preform core rod, and at least one second overclad tube surrounding the first overclad tube. A quartz disc with or without one or more quartz spacers is used for supporting the preform core rod and the first overclad tube within the additional overclad tubes.

Collapsing a multitube assembly and subsequent optical fiber drawing in the same furnace

A singlemode optical fiber 700 having very low loss at 1385 nm, and a practical method for making same are disclosed. A core rod 20 is fabricated using vapor axial deposition to have a deposited cladding/core ratio (D/d) that is less than 7.5. The core rod is dehydrated in a chlorine- or fluorine-containing atmosphere at about 1200.degree. C. to reduce the amount of OH present to less than 0.8 parts per billion by weight, and then consolidated in a helium atmosphere at about 1500.degree. C. to convert the porous soot body into a glass. The consolidated core rod is elongated using an oxygen-hydrogen torch that creates a layer of OH ions on the surface of the rod that are largely removed by plasma etching. Finally, the core rod is installed in a glass tube 40 having a suitably low OH content. Thereafter, the tube is collapsed onto the rod to create a preform 60. Conventional methods are employed for drawing an optical fiber from the preform and applying one or more protective coatings 75, 76. The disclosed method is suitable for commercial production of low-OH fiber. Significantly, the fiber's loss at 1385 nm is reduced to a level that is less than its loss at 1310 nm, thereby rendering the entire wavelength region 1200-1600 nm suitable for optical transmission. In particular, wave-division-multiplex systems are now available to transmit optical signals over distances greater than 10 km in the wavelength region between 1360 nm and 1430 nm.

Method of making a fiber having low loss at 1385 nm by cladding a VAD

In a flame hydrolysis method for depositing glass soot used ultimately to make optical fiber, a reactant that forms the glassy soot stream is delivered to the torch (20) in liquid form and an ultrasonic nozzle (34) in the torch atomizes the reactant or breaks the reactant into a fine mist without the use of a gas.

Method of glass soot deposition using ultrasonic nozzle

A fluorine-doped silica soot cylinder (11) is consolidated by containing it within an encapsulation structure (29) within a furance (21). The atmosphere within the encapsulation structure is kept substantially stagnant during the consolidating, and the volume enclosed by the encapsulation structure (29) is only slightly greater than the volume of the soot cylinder (11). A gap (52) between the volume enclosed by the encapsulating structure and the furnace is kept small enough to impede gas flow to a sufficient extent that the atmosphere within the encapsulating structure (29) is substantially stagnant during consolidation. During consolidation, fluorine concentration within the encapsulation structure (29) is uniformly distributed within the soot cylinder (11).

Method for consolidating doped glass using an encapsulating structure

A fluorine-doped silica soot cylinder (11) is consolidated by containing it within an encapsulation structure (29) within a furnace (21). The atmosphere within the encapsulation structure is kept substantially stagnant during the consolidating, and the volume enclosed by the encapsulation structure (29) is only slightly greater than the volume of the soot cylinder (11). A gap (52) between the volume enclosed by the encapsulating structure and the furnace is kept small enough to impede gas flow to a sufficient extent that the atmosphere within the encapsulating structure (29) is substantially stagnant during consolidation. During consolidation, fluorine concentration within the encapsulation structure (29) is uniformly distributed within the soot cylinder (11).

Method of fluorine doped modified chemical vapor deposition

Method and apparatus are provided for overcladding a preform rod (22). The preform rod is aligned with and inserted into an overcladding tube (30). The outer diameter of the preform rod and the inner diameter of the tube are such that the clearance between the tube and the rod does not exceed a predetermined value. Successive increments of length of the tube and rod therein are subjected to a controlled zone of heat while the pressure inside the tube is maintained at a value which is substantially less than that outside the tube. This causes the tube to be collapsed onto the preform rod to provide an overclad preform and subsequently a drawn optical fiber in which the overcladding is substantially concentric with respect to the optical fiber core.

Method of and apparatus for overcladding a glass rod

A lightguide preform is fabricated by depositing a thin carbon layer (40) on a cylindrical glass mandrel (30) and further depositing a plurality of glassy soot layers (32) thereover. The resulting composite structure is heated, in a furnace, at a low temperature to remove the carbon layer (40) and then heated at an elevated temperature to consolidate the glassy soot layers on the glass mandrel to form the lightguide preform.

Growing community of inventors

Alpharetta, GA, United States of America

Thomas John Miller