At&t Bell Laboratories

Lucent Technologies Inc.

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

John T Chapin

Raffaele A Sabia

Montri Viriyayuthakorn

Thomas O Mensah

Charles W Jackson

Mickey R Reynolds

Terry D Mathis

James Robert Holman

Larry L Bleich

Philip Nelson Gardner

Lionell Graham

Steven John Cassady

A fiber optic cable having stress indicating means and a method for making same. The stress indicating means provides a cost effective method for determining whether an optical cable has been bent, stressed or otherwise mishandled, which may cause optical loss when the cable is placed in service. Broadly stated, the fiber optic cable according to the instant invention includes an optical fiber, comprised of a core and a cladding and a stress indicator concentrically disposed about the fiber that changes color when subjected to stress. A technician can thereby visually identify cables that have been bent or mishandled and subject them to testing before installation.

Optical fiber cable products having a stress indicating capability and

The present invention provides a color-coded optical fiber cable and a method for manufacturing the color-coded optical fiber cable. The optical fiber cable of the present invention comprises a glass fiber, a buffer surrounding the fiber, which may be comprised of nylon, an aramid fiber strength member surrounding the fiber buffer, and an outer sheath surrounding the aramid fiber strength member. In accordance with a first embodiment of the present invention, optical fiber cables are color coded by using aramid fiber strength members of different colors. Once a color-coded aramid fiber strength member has been placed about the fiber buffer, it is surrounded by a light-transmissive outer sheath so that the color of the aramid fiber strength member can be easily ascertained, even when the optical fiber cable is wound up on a reel. When employed with a duplex cable, this embodiment allows a technician to easily determine which miniature jumper cable of the duplex cable is the transmit jumper cable and which is the receive jumper cable. In accordance with a second embodiment of the present invention, an optical fiber cable is color coded by placing a colored jacket about the aramid fiber strength member of the optical fiber cable. An outer light-transmissive jacket is then placed about the colored jacket. When a duplex optical fiber cable is color coded in accordance with this embodiment, the colored jackets of each of the jumper cables are simultaneously covered with the light-transmissive outer sheath by extruding the light-transmissive outer sheath over the colored jackets. The light-transmissive outer sheath holds the jumper cables together. The colored jackets of the jumper cables can be easily seen by a technician through the outer light-transmissive jacket of the duplex cable. The present invention can be used in a similar manner to color code optical fiber jumper cables contained in optical fiber quad cables and in optical fiber break-out cables.

Color-coded optical fiber cable and a method for manufacturing the same

A coaxial cable with standard coaxial structure of central conductor, foamed polyethylene dielectric, and outer conductor and having a jacket that provides sufficient flame resistance and smoke generation to allow the cable to be used in plenum spaces. The jacket includes a halogenated polymer with a heat of combustion less than 7000 BTU per pound and including a free-radical scavenger.

Coaxial cable for plenum applications

A buffered optical fiber (20) includes an optical fiber (21) comprising a core and a cladding. Typically, the optical fiber is enclosed by at least one layer (23) of coating material. The optical fiber is enclosed by a plastic buffer layer (30). Interposed between the optical fiber and the buffer layer is a boundary layer (40). Importantly, the boundary layer of the present invention is a low modulus material applied as a substantially thick layer relative to the buffer layer. In a preferred embodiment, the wall thickness of the boundary layer is about one-forth to one-third the wall thickness of the buffer layer. However, depending on the particular materials selected for the buffer and boundary layer, the wall thickness of the boundary layer can be as thin as one-twenty-fifth (1/25) of the buffer layer. As a result of the present design, there is sufficient adhesion between the buffer layer and the underlying coating material to maintain the buffer layer in place during normal use of the buffered optical fiber. On the other hand, the adhesion is low enough so that the buffer layer may be removed upon the application of reasonably low mechanical stripping forces. Advantageously, the boundary layer also allows the selective removal of the optical fiber coating material as well as the plastic buffer layer.

Buffered optical fiber having a strippable buffer layer

An optical fiber package (20) is provided by winding a plurality of convolutions in a plurality of layers on a bobbin. To each layer is applied an adhesive material (45) which in a preferred embodiment is a mixture comprising a reactive silicone copolymer resin, a solvent system which includes an aromatic constituent, a catalyst and a wetting agent. The mixture has a modulus behavior which is relatively stable with respect to time throughout a relatively wide operating temperature. Inasmuch as the solvent system and the method of application of the mixture are effective to control the rate of precipitation and the rate of cure of the silicone constituent, the surface roughness of the convolutions is controlled. After the desired number of convolutions have been wound, the package is subjected to a heat treatment which relieves stresses in the wound fiber and which completes the cure of the adhesive material. The adhesive material is effective to hold the convolutions together sufficiently to allow transport and deployment and to allow the convolutions constantly to be payed off over a relatively wide temperature range and over a relatively wide range of payout speeds without the use of excessive force and without breakage.

Methods of providing an optical fiber package

An optical fiber package (20) is provided by winding a plurality of convolutions in a plurality of layers on a bobbin. To each layer is applied an adhesive material (45) which in a preferred embodiment is a mixture comprising a relative silicone copolymer resin, a solvent system which includes an aromatic constituent, a catalyst and a wetting agent. The mixture has a modulus behavior which is relatively stable with respect to time throughout a relatively wide operating temperature. Inasmuch as the solvent system and the method of application of the mixture are effective to control the rate of precipitation and the rate of cure of the silicone constituent, the surface roughness of the convolutions is controlled. After the desired number of convolutions have been wound, the package is subjected to a heat treatment which relieves stresses in the wound fiber and which completes the cure of the adhesive material. The adhesive material is effective to hold the convolutions together sufficiently to allow transport and deployment and to allow the convolutions constantly to be payed off over a relatively wide temperature range and over a relatively wide range of payout speeds without the use of excessive force and without breakage.

Guided vehicle system

Optical fiber package and methods of making

A mineral-oil-free composition of matter useful as a cable splice encapsulant comprises between about 20% and about 60% polyurethane, by weight of the cured encapsulant, the balance comprising plasticizer(s) and optionally, additives such as catalysts, antioxidants and fungicides.

Mineral-oil-free encapsulant composition

A mineral oil-free cured cable splice encapsulant comprises between about 20% and about 60% polyurethane, by weight of the cured encapsulant, the balance comprising diluent(s) and/or plasticizers, and typically has a cure and typically has a cure time of at least 50 minutes at 25.degree. C. The relatively long cure time, together with other properties of the material, including a viscosity typically between 150 and 1500 centipose, and relatively good 'bonding' to plastic-insulated conductors, results in improved water-intrusion resistance of splices enveloped in the novel encapsulant.

Articles comprising a mineral-oil-free encapsulant

An article for the sustained release of an insecticide into the ambient air comprises an elastomeric matrix, with the insecticide dissolved in the matrix. The matrix material has a modulus between about 10.sup.4 Pa and about 10.sup.8 Pa at 23.degree. C., and a glass transition temperature less than 0.degree. C. The matrix comprises polyurethane formed by reacting hydroxyl-terminated polybutadiene or polyisoprene and 4,4' diphenylmethane diisocyanate, and the insecticide is 2,2' dichlorovinyl dimethyl phosphate. The insecticide-containing matrix is contained in a plastic bottle, and typically protected against inadvertent skin contact by means of a dermal barrier. The article also comprises means for activating the article such that, prior to activation, release of insecticide into the ambient air is prevented, whereas such release can take place after activation. Exemplary activation means comprise a metal foil seal of the plastic bottle. The article is effective in controlling insect infestation (e.g., ants, fire ants, bees, wasps, cockroaches) in enclosures, e.g., enclosures of the type used to protect outdoor utility equipment.

Article comprising an elastomeric controlled release insecticide

Means for the sustained release of an active agent into the environment comprise an elastomeric matrix and the active agent contained in the matrix. The matrix material has a modulus between about 10.sup.4 Pa and about 10.sup.8 Pa at 23.degree. C., and a glass transition temperature less than 0.degree. C. The matrix comprises polyurethane formed by reacting polyol and isocyanate, and the active agent can be any biologically or nonbiologically active agent that is compatible with the matrix, e.g., the insecticide 2,2' dichlorovinyl dimethyl phosphate. The inventive sustained release system has particularly advantageous release properties, e.g., it typically can release more than 70% of the active agent contained in the matrix.

Elastomeric controlled release formulation and article comprising same

A varnish suitable for spray coating on plastic insulated copper conductors restores cracked or damaged insulation. The varnish cures by reaction in air upon application to the conductors. The varnish comprises drying oil (typically, tung oil and castor oil), phenolic resin, metallic catalysts, and solvents.

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Alpharetta, GA, United States of America

John T Chapin