International Telephone and Telegraph Corporation

Itt Corporation

Alcatel USA

Alcatel Na, Inc.,

Dipak R Biswas

Dilip K Nath

Satyabrata Raychaudhuri

Joseph C Williams

Jeff P Garmon

A Dahlgren Vaughan

In the manufacture of optical fibers, at least a portion of a preform of optical glass is heated into a molten state and drawn to create an optical fiber of the desired diameter. To cool the fiber during the drawing process and prior to coating thereof, the invention contemplates providing a cooling device with a laminar flow of inert gas therein to surround and cool the fiber.

Inert atmosphere cooler for optical fibers

An optical fiber which has just been drawn from an optical preform is provided with two external hermetic coatings. The primary coating is a metallic or dielectric coating provided by, for example, using a heterogeneous nucleation thermochemical deposition (HNTD) technique. This technique involves passing the fiber through a reaction zone which contains a gaseous medium that includes a reactant which decomposes, or a mixture of reactants which chemically react, at a predetermined temperature, to form the material of the coating. Such predetermined temperature is available from the heat of the fiber forming process which is retained at the fiber surface by means of a shielding element so that additional heating means is not required. The second coating may be deposited, by for example, using an HNTD or a chemical vapor deposition process. The resulting fiber may then be provided with an additional polymer coating layer.

Method of applying hermetic coating on optical fiber

Solid fibers or capillaries are coated with a metal, alloy or dielectric capable of withstanding temperatures in excess of 300.degree. C. and preferably 500.degree. C. The coating is deposited by a heterogeneous nucleation thermochemical deposition process occurring on the surface of the fiber.

Glass fibers and capillaries with high temperature resistant coatings

An optical fiber which has just been drawn from an optical preform is provided with two external hermetic coatings. The primary coating is a metallic coating provided by, for example, using a heterogeneous nucleation thermochemical deposition technique. This technique involves passing the fiber through a reaction zone which contains a gaseous medium that includes a reactant which decomposes, or a mixture of reactants which chemically react, at a predetermined temperature to form the material of the coating. The second coating is provided by immersing the fiber in a deposition bath containing a liquid medium which includes at least one reactant capable of deposition onto the primary coating to form a secondary coating. The deposition process may be achieved by applying a current through the medium at a predetermined temperature or by including reactants in the medium which will deposit at predetermined temperatures without applying a current. The resulting fiber may then be provided with an additional polymer coating layer.

Hermetic coating for an optical fiber

An optical fiber which has just been drawn from an optical preform is provided with an external hermetic coating by using a heterogeneous nucleation thermochemical deposition technique. This technique involves passing the fiber through a reaction zone which contains a gaseous medium that includes a reactant which decomposes, or a mixture of reactants which chemically react, at a predetermined temperature to form the material of the coating. Only the fiber but not the gaseous medium surrounding the same is heated to the predetermined temperature, especially by directing radiation onto the exposed circumferential surface of the fiber, so that the decomposition or the chemical reaction takes place directly on the exposed surface of the fiber rather than in the gaseous medium, accompanied by simultaneous deposition of the coating material on the exposed surface of the fiber. The resulting fiber with hermetic coating can then be provided with an additional polymer coating layer. The apparatus for performing this technique includes a reactor including a transparent wall which circumferentially bounds a reaction chamber constituting the reaction zone, and a heating arrangement including two infrared radiation sources located externally of the transparent wall and each associated with a part-elliptical mirror which reflects the radiation toward the transparent wall and through the same onto the exposed surface of the fiber.

Hermetic coating by heterogeneous nucleation thermochemical deposition

A metallic material coating is applied to the external surface of a freshly drawn optical fiber while such surface is still pristine by passing the optical fiber through a body of liquid metal-organic material which forms a layer on the fiber, and by subsequently removing all non-metallic components from the layer of metal-organic material by volatilizing the same. The optical fiber with the layer metal-organic material is passed through a baking oven in which at least the layer is heated to a baking temperature at which organic materials present in the metal-organic material are volatilized and the remainder is baked to the fiber. Then, at least the layer is fired in a firing chamber at a higher temperature at which the metal-organic material is decomposed into its volatile non-metallic and non-volatile metallic components, the latter remaining in the layer and the former becoming volatile and leaving the layer. Preferably, at least one layer of synthetic plastic material is applied over the thus obtained metallic layer. When the firing is done in an inert or reducing atomsphere, the metallic material is in its elemental form, while it is in its metal-oxide form when the firing operation is accomplished in an oxidizing atmosphere. Various printing inks and/or resinates may be used as the starting metal-organic materials in the process according to the invention.

Method of an arrangement for coating optical fibers with metallic

A tubular formation of particulate optical material is formed by a layer slurry deposition process which involves spraying layer after layer of slurry containing particles of the optical material onto a rotating rod-shaped bait. The composition of the slurry and particularly the index of refraction of the optical material may be varied from one layer to another or from one group of layers to another to obtain a graded or stepped refraction index profile in the formation, in an optical preform formed therefrom, and ultimately in the fiber drawn from the optical preform. The particles of the slurry are suspended in a liquid vehicle which evaporates in the spray stream or shortly after deposition, and are coated with an organic binder which holds them together in the layer and in the formation, so that the formation is self-supporting. Then, the organic binder is removed and the formation is sintered, followed by a collapse of the sintered tubular formation into the optical preform in the form of a solid rod. Then, optical fiber of the desired optical properties can be drawn from the optical preform. The associated apparatus includes a spray gun aimed at the bait rod, and a receptacle for the slurry from which the slurry is supplied to the spray gun. The bait rod is clamped in chucks and is rotated, while the spray gun moves in the axial direction of the bait rod in a plurality of passes to deposit the formation on the bait rod.

Growing community of inventors

Roanoke, VA, United States of America

Dipak R Biswas