Patent US4917087A successfully refreshed from Google Patents.
EP0154026A2
Expired / Lapsed
EP
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A monomode optical fibre and a method of manufacture
Assignee: British Telecommunications PLC
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Filing: 1981-07-16
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Granted: —
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Expires: 2001-07-16
Abstract
Abstract A glass fibre for optical communication is formed by a vapour deposition process on the inside surface of pure silica substrate tube. The substrate forms the outer cladding whilst the inner and core are formed by the deposited layers. An intermediate layer of the cladding has a refractive-index similar to pure silica but due to compensating dopants. Thus deposition and sintering temperature is reduced. The inner layer of the cladding is however undoped pure silica, thus reducing absorbtion losses in this important region. The inner layer is described as having an outer radius of 1.5 to 2 times the radius of the core. A step in a process for making optical fibres comprising collapsing a tubular substrate to provide a preform is carried out in a stream of pure chlorine vapour acting as a drying agent.
Inventors
- 👤 Benjamin J. Ainslie
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 17:06
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/036; G02B6/03616; G02B6/03622; G02B6/03633; C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/018; C03B37/01861; C03C; C03C13/00; C03C13/04; C03C13/045; G02B6/03627; C03B2203/00; C03B2203/10; C03B2203/22; C03B2203/24; Y; Y10; Y10S; Y10S65/00; Y10S65/90
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
100 words
A monomode optical fibre having a core and a cladding region, wherein the core comprises silica doped with a refractive-index-increasing substance, and the cladding has an outer region comprising substantially undoped silica, with the remainder of the cladding including regions of silica doped with both refractive-index-increasing and refractive-index-decreasing substances, and characterised in that the concentration of said dopants in said remainder of the cladding is less towards the core of the fibre so that there exists at least an intermediate region of the cladding where the concentration of said dopants is greater than the remaining inner region of the cladding.
Claim 2
Dependent Claim
100 words
A monomode optical fibre having a core and a cladding region, wherein the core comprises silica doped with a refractive-index-increasing substance, and the cladding has an outer region comprising substantially undoped silica, with the remainder of the cladding including regions of silica doped with both refractive-index-increasing and refractive-index-decreasing substances, and characterised in that the concentration of said dopants in said remainder of the cladding is less towards the core of the fibre so that there exists at least an intermediate region of the cladding where the concentration of said dopants is greater than the remaining inner region of the cladding.
Claim 3
Dependent Claim
35 words
An optical fibre as claimed in claim 1 characterised in that the inner region of the cladding has an outer radius in the range from 1.5 to 2 times the radius of the core region.
Claim 4
Dependent Claim
48 words
An optical fibre as claimed in claim 1 or claim 2 characterised in that said dopant substances, where they are present in the cladding, are present in such relative quantities that the refractive-index of the cladding where they are present is substantially equal to that of pure silica.
Claim 5
Dependent Claim
26 words
An optical fibre as claimed in any one of claims 1 to 3 characterised in that the inner region of the cladding comprises substantially undoped silica.
Claim 6
Dependent Claim
36 words
An optical fibre as claimed in any one of claims 1 to 3 characterised in that the inner region of the cladding has a diminished concentration of said dopants, without including a substantially undoped silica region.
Claim 7
Dependent Claim
25 words
An optical fibre as claimed in any one of claims 1 to 5 characterised in that the refractive-index-increasing substance in the core is germanium dioxide.
Claim 8
Dependent Claim
25 words
An optical fibre as claimed in any one of claims 1 to 6 chracterised in that the refractive-index-increasing substance in the cladding is phosphorus pentoxide.
Claim 9
Dependent Claim
24 words
An optical fibre as claimed in any one of claims 1 to 7 characterised in that the refractive-index-decreasing substance in the cladding is fluorine.
Claim 10
Dependent Claim
94 words
A method of manufacturing a monomode optical fibre as claimed in any one of claims 1 to 8 which comprises the steps of depositing successive layers of silica or doped silica on the inner surface of a tubular silica substrate by thermal oxidation of a vapour including a silicon compound, and, as necessary, dopant materials, and subsequently heating the tube to cause it to collapse into a preform of the fibre, wherein the composition of the vapour is controlled such that said layers correspond to the cladding and core layers specified in claim 1.
References Cited (Backward Citations)
No citation records indexed.
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