International Telephone and Telegraph Corporation

Eotec

Mokhtar S Maklad

Charles K Kao

James E Goell

Gary W Bickel

Francis I Akers

Trevor Wayne MacDougall

Paul Eric Sanders

David A Krohn

Pablo C Pureza

Adolf R Asam

George H Sigel, Jr

William L Thomas

A method of producing a hollow core optical fiber comprises the steps of depositing a thermal buffer layer on the interior wall of a silica tube, depositing a film of germanium silicate cladding on said buffer layer, heating the composite structure so formed to its drawing temperature, and drawing the heated composite structure to form a hollow core optical fiber.

Low loss infrared transmitting hollow core optical fiber method of

A method for manufacturing hollow core optical fibers is disclosed comprising continuously feeding a glass rod of the desired cladding composition into a high temperature furnace with the rod in line contact with the inner surface of the glass tube. The glass transition temperature of the rod is substantially lower than the glass transition temperature of the glass tube. The glass rod composition is uniformly distributed on the glass tube inner wall as it enters the furnace hot zone. The ratio of the rod diameter to the glass tube inner diameter and the drawing temperature determine the coating thickness of the glass cladding on the inner surface of the glass tube. As the coated tube is passed through the furnace hot zone peak, the optical fiber is drawn. The rod and tube feed rate, the drawing temperature of the rod and glass tube and the drawing rate of the coated glass tube are selected to yield a hollow core optical fiber, with preselected interior and exterior diameters.

Method of manufacturing hollow core optical fibers

A process for making an optical fiber includes the steps of inserting a rod of the core glass composition into a closed tube made of the cladding glass. The diameter of the rod is substantially less than the inner diameter of the tube. The glass transition temperature of the core glass must be substantially lower than the glass transition temperature of the cladding and the rod is placed in contact with the tube along its entire length. When heat is applied to the lower portion of the rod and tube, the rod melts and forms a thin film on the inner surface of the tube which can rapidly be fined to a relatively pure glass. This melted glass forms a melt pool in the bottom of the tube, and the tube and pool can then be drawn into a fiber with the desired characteristics. A process for making a graded optical fiber utilizing a modified chemical vapor deposition process is also disclosed wherein a cladding glass is entrained on the inner surface of a tube substrate. A core rod is then inserted into the coated substrate tube. At the high drawing temperatures, ion exchange occurs between the core glass and the cladding glass to produce low loss graded optical fibers having an improved refractive index profile. Low loss, single mode optical fibers and single polarization guidance fibers can also be made by this method.

Method of manufacturing optical fibers

The stress-induced birefringent single mode optical fiber includes an optical core having a high refractive index and a high thermal expansion coefficient. An arrangement formed from an optical material having a low refractive index and a low thermal expansion coefficient is disposed to engage the outer surface of the core tangentially at opposite ends of a diameter of the core to establish a stress therein. Air encompasses the remainder of the outer surface of the core to provide a light guiding cladding for the core and, hence, the fiber itself. The arrangement to establish the stress may include a pair of flat plates engaging the outer surface of the core tangentially which are entrapped in a circular tube which is concentric with the core such that air is entrapped between the plates and the circular tube to provide the light guiding cladding. Alternatively, an elliptical tube is provided to engage the outer surface of the core at the minor axis of the elliptical tube to provide the desired stress in the fiber. In this case air is enclosed in the elliptical tube to provide the light guiding cladding.

Stress-induced birefringent single mode optical fiber and a method of

The fatigue resistant optical fiber is fabricated by producing an optical fiber having an electrically conducting surface, heating the produced optical fiber, and coating the heated optical fiber with a material impervious to water and water vapor.

Method of fabricating fatigue resistant optical fibers

A method for fabricating a fiber with optical cores of diameters between 2 to 20 microns is depicted. A first step includes the fabrication of a step-index preform of predetermined dimensions. The preform is drawn into a conventional fiber by conventional techniques resulting in a fiber having an outer diameter of about 120 microns or larger. The fiber is then emplaced in a glass tube. The tube is collapsed on the fiber by heating the same resulting in a second preform. This preform is again drawn into a fiber by conventional techniques to obtain a final fiber having core dimensions indicative of single mode operation with compatible outer diameters.

Method of fabrication of single mode optical fibers or waveguides

High-strength optical preforms and optical fibers, particularly useful in light-wave communication systems, are fabricated by techniques producing high surface compressive forces in thin outer layers. These result in substantially increased fiber tensile strength, durability, and fiber life. High surface stresses are achieved in three-layer and four-layer preforms and fibers by employing particular combinations of core, cladding, and layer compositions, dopants, coefficients of thermal expansion, and glass transition temperatures. Various suitable manufacturing methods are disclosed using chemical vapor deposition techniques. For example, preforms may be fabricated by external deposition of layers on a drawn core-glass rod, or by internal CVD methods in which layers are sequentially deposited within hollow tubular silica substrates that are then collapsed into solid preforms by known techniques. In the internal deposition methods, preform finishing techniques are also disclosed for removing excess substrate material so as to leave a high-strength compressive layer of substantially pure silica.

High-strength optical preforms and fibers with thin, high-compression

A large optical preform is fabricated by rotating a platform about its axis while advancing the platform away from a series of nozzles. Each nozzle is arranged to generate an annular ring associated with the preform by a vapor phase oxidation technique. The vapor content introduced by each nozzle is tailored to provide a large diameter optical preform possessing step index, single mode or graded index capabilities. The preform thus produced is then drawn into elongated optical fiber cables having the above described properties.

Method of fabricating large optical preforms

An optical fiber or similar article is coated by directing the fiber through a spherical mixing vessel. Two silicone RTV components are directed by means of an annular feed mechanism into the mixing vessel at predetermined flow rates. The motion of the fiber directed through the vessel produces a churning or agitation of the silicone components to uniformly and homogeneously coat the fiber with the mixed components and provide a protective elastomeric coating about the fiber.

Apparatus and methods of coating filaments with polymers

A method of forming optical fibers in a continuous manufacturing process employs a heated mandrel with a predetermined taper at one end. Glass forming materials are applied to the mandrel by chemical vapor deposition along the taper to provide a corresponding glass concentration gradient along the taper. The molten glass materials are drawn in a continuous process without an intermediate preform stage.

Continuous fiber fabrication process

A method of fabricating a low loss single mode optical fiber having an elliptically shaped core comprising subjecting a multi-layered coated substrate having at least a barrier, cladding and core layer to partial collapse, first on one side and then on the other side, to produce an intermediate product having a substantially cross-sectional elliptical shape of at least the core layer. This is followed by collapsing the composite structure into a cylindrical shaped optical fiber preform having an elliptically shaped core portion which is then heated and drawn into a single mode optical fiber having an elliptically shaped core portion.

Method of fabricating an elliptical core single mode fiber

Optical communication fibers having improved fatigue resistance are provided by encapsulating the fibers in a water impervious material. The water impervious material prevents the interaction of water with glass along the fiber outer surface and prolongs the operational life-time of the fibers.

Water resistant high strength fibers

Optical fibers of silica and plastic composition are rendered relatively stable to nuclear radiation induced optical losses by preirradiating with a high initial radiation dosage. Subsequent exposure of the radiation hardended fibers produce substantially lower radiation induced optical loss and faster fiber transmission recovery rates.

Radiation hardness of optical fibers

A low loss multilayer optical fiber having good transmission propertiesin the infrared region of the spectrum is produced by depositing the core and cladding materials on the inner surface of a collapsible silica tube in the absence of moisture. A barrier layer is interposed between the silica tube and the cladding to prevent the migration of OH and transition metal ions during the tube collapsing and fiber drawing processes.

Low loss multilayer optical fiber

A method and means is disclosed for continuously monitoring an optical fiber's attenuation or loss as it is being formed, which includes: a light source, which may be the heated fiber itself during drawing operations or an external source; passing the light through the fiber being produced; positioning the end of the fiber in a holder adjacent to a light detector, for example a photodiode with or without passing the transmitted light through a filter; detecting the light transmitted by the fiber from the light source; converting the detected light into an electrical equivalent signal; amplifying the signal if necessary and recording or observing the changes in the signal to determine an objective measure of the optical fiber's attenuating characteristic.

Growing community of inventors

Roanoke, VA, United States of America

Mokhtar S Maklad