EP0243010A1
Expired / Lapsed
EP
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Preparation of glass fibre
Assignee: British Telecommunications PLC
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Filing: 1987-03-27
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Granted: —
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Expires: 2007-03-27
Abstract
Abstract Rare earth or other metallic elements, eg Nd and Er, are introduced into optical glass fibre for telecommunications by evaporating a suitable salt, eg NdCl 3 or ErCl 3 , from a glass sponge (12) into the gas stream used to deposit core or other material. Preferred sponges (12A, 12B, 12C) are in the form of tubes having an outer impervious layer and an inner porous layer. These sponges (12A, 12B, 12C) are conveniently made by MCVD and the impregnation is preferably carried out using an alcoholic solution of the impregnant.
Inventors
- 👤 Benjamin James Ainslie
- 👤 Susan Patricia Craig
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 04:11
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/018; C03B37/01807; C03B2201/00; C03B2201/06; C03B2201/20; C03B2201/28; C03B2201/30; C03B2201/31; C03B2201/34
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
29 words
A source for providing one or more metal compounds, into MCVD which source takes the form of an inert, solid, porous sponge impregnated with at least one metal compound.
Claim 2
Dependent Claim
29 words
A source for providing one or more metal compounds, into MCVD which source takes the form of an inert, solid, porous sponge impregnated with at least one metal compound.
Claim 3
Dependent Claim
13 words
A source according to claim 1, wherein the sponge is formed of silica.
Claim 4
Dependent Claim
21 words
A source according to either claim 1 or claim 2, in which the impregnant consists of at least one metal salt.
Claim 5
Dependent Claim
14 words
A source according to claim 3, wherein the or each salt is a halide.
Claim 6
Dependent Claim
14 words
A source according to claim 4, wherein the or each salt is a chloride.
Claim 7
Dependent Claim
21 words
A source according to any one of the preceding claims, in which the or each metal compound is involatile at 100°C.
Claim 8
Dependent Claim
23 words
A source according to any one of the preceding claims, wherein the metal of the or each metal compound is a rare earth.
Claim 9
Dependent Claim
15 words
A source according to claim 7, wherein the rare earth metal is neodymium or erbium.
Claim 10
Dependent Claim
17 words
A source according to any one of the preceding claims, wherein the sponge has a tubular configuration.
Claim 11
Dependent Claim
19 words
A source according to claim 9, wherein the sponge has an outer impervious layer and an inner porous layer.
Claim 12
Dependent Claim
43 words
A method of making a source according to claim 10, which method comprises depositing a porous silica layer on the inner surface of a substrate tube by MCVD, said MCVD being performed at a temperature below the sintering temperature of the deposited silica.
Claim 13
Dependent Claim
23 words
A method according to claim 11, wherein the product of the MCVD is soaked in a solution of the impregnant and dried thereafter.
Claim 14
Dependent Claim
12 words
A method according to claim 12, wherein the solvent is an alcohol.
Claim 15
Dependent Claim
11 words
A method according to claim 13, wherein the alcohol is ethanol.
Claim 16
Independent Claim
26 words
A method according to any one of claims 12 to 14, wherein the solute is NdC1 3 .6H 2 0 or ErCl 3 .CH 2 O.
Claim 17
Independent Claim
74 words
A method of preparing a precursor of optical fibre for telecommunications which comprises depositing a plurality of glass layers on the inner surface of a substrate tube by MCVD, characterised in that the deposition is carried out with a source according to any one of claims 1 to 10 located in the substrate tube upstream of the deposition zone and that said source is heated to volatilise impregnant during the deposition of selected layers.
Claim 18
Dependent Claim
15 words
A method according to claim 16, wherein the selected layers are the core precursor layers.
Claim 19
Dependent Claim
27 words
A method according to either claim 16 or claim 17, wherein the source is prepared by a method according to any one of claims 11 to 15.
Claim 20
Independent Claim
29 words
A method of preparing glass fibre which comprises making a precursor according to any one of claims 16, 17 or 18 and then drawing the precursor into the fibre.
References Cited (Backward Citations)
US3971645A
Cited
US4597787A
Cited
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