Itt Corporation

Alcatel USA

Satyabrata Raychaudhuri

Dipak R Biswas

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

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.

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Roanoke, VA, United States of America

Satyabrata Raychaudhuri