Optical fiber fabrication and resulting product
AssigneeBell Telephone Laboratories, Incorporated
InventorsJohn B. MacChesney, Paul B. O'Connor
Life of this patent
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Abstract
A preform for fabrication of a glass fiber optical transmission line is prepared by chemical reaction of vapor ingredients within a glass tube. Reaction, which may be between chlorides or hydrides of, for example, silicon and germanium with oxygen, occurs preferentially within a constantly traversing hot zone. Flow rates and temperature are sufficient to result in glass formation in the form of particulate matter on the inner surface of the tube. This particulate matter deposits on the tube and is fused with each passage of the hot zone. Continuous rotation of the tube during processing permits attainment of higher temperatures within the heated zone without distortion of the tube.
Claims26
Process for fabrication of a glass fiber optical transmission line, comprising a core section and a cladding, wherein the cladding has an index of refraction of a value lower than the maximum index of the core for energy of the wavelength to be transmitted, comprising introducing a moving stream of a vapor mixture including at least one compound glass-forming precursor together with an oxidizing medium into a tube while heating the tube so as to react the said mixture and produce a glassy deposit on the inner surface of the tube, characterized in that heating of tube and contents are by a moving hot zone produced by a correspondingly moving heat source external to the tube in that combustion within the tube is avoided and in that temperature within the hot zone, composition of the vapor mixture, and rate of introduction of the vapor mixture are maintained at values such that at least a part of the reaction takes place within the gaseous mixture at a position spaced from the inner walls of the said tube, thereby producing a suspension of oxidic reaction product particulate material, whereby the particulate material while traveling downstream comes to rest on the inner surface of the tube within a region which extends from a position within the said hot zone, the moving zone serving the dual functions of:
- nucleation site for homogeneous reaction to produce particulate matter;
- and consolidation site for previously produced particulate matter.
A process of fabricating a preform for drawing into a glass fiber optical transmission line comprising introducing into a rotating glass tube, the inner surface of which is made up of a glass having a first refractive index, a gaseous mixture of oxygen and chlorides of silicon and germanium while a hot zone moving repeatedly along said tube is produced inside said tube by a heat source external to said tube, while maintaining the temperature of the hot zone sufficiently high and introducing said silicon and germanium chlorides at a sufficient rate that the silicon and germanium are converted to an oxidic product at least partly in the form of entrained particulate material which comes to rest on the inner surface of the tube, the said temperature being sufficiently high to effect fusion of said deposited particulate material into a unitary glassy layer of a refractive index higher than said first refractive index.
Dependencies are inferred from the claim text.