EP0109192A1
Expired / Lapsed
EP
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Method of producing optical fiber preform
Assignee: Hitachi Ltd
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Filing: 1983-10-14
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Granted: —
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Expires: 2003-10-14
Abstract
Abstract A method of producing a preform for a single-polarization optical fiber wherein a glass rod 3 which in the fiber is to be a core or a glass rod which is to be a clad and a core is inserted into a quartz tube 1 which has on its inner wall surface (a) a thin glass film 2 which is to be a clad layer, (b) a thin glass film which is to be a jacket layer or (c) thin glass films which are to be a jacket layer and a clad layer. Then, with its internal pressure reduced, the tube 1 is heated to become solid, so that at least one of the clad and the jacket of the optical fiber preform becomes elliptic in cross section.
Inventors
- 👤 Hiroyoshi Matsumura
- 👤 Toshio Katsuyama
- 👤 Tsuneo Suganuma
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 20:08
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/01205; C03B37/01225; C03B37/01248; C03B37/01211; C03B37/01217; C03B37/014; C03B37/018; C03B2203/00; C03B2203/10; C03B2203/22; C03B2203/24; C03B2203/30
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
151 words
A method of producing an optical fiber preform comprising the steps of (i) forming (a) a thin glass film which in the fiber is to be a clad layer, (b) a thin glass film which is to be a jacket layer, or (c) thin glass films which are to be a jacket layer and a clad layer, on an inner wall of a glass mother tube, (ii) inserting (a) a glass rod which is to be a core or (b) a glass rod which is to be a core and a clad, into the glass mother tube produced by step (i), and (iii) heating the glass mother tube with the glass rod inserted therein to a predetermined temperature while the pressure inside said glass mother tube is lower by a predetermined value than the pressure outside -said glass mother tube, said glass mother tube being thus made into a solid preform.
Claim 2
Independent Claim
151 words
A method of producing an optical fiber preform comprising the steps of (i) forming (a) a thin glass film which in the fiber is to be a clad layer, (b) a thin glass film which is to be a jacket layer, or (c) thin glass films which are to be a jacket layer and a clad layer, on an inner wall of a glass mother tube, (ii) inserting (a) a glass rod which is to be a core or (b) a glass rod which is to be a core and a clad, into the glass mother tube produced by step (i), and (iii) heating the glass mother tube with the glass rod inserted therein to a predetermined temperature while the pressure inside said glass mother tube is lower by a predetermined value than the pressure outside -said glass mother tube, said glass mother tube being thus made into a solid preform.
Claim 3
Dependent Claim
33 words
A method as defined in claim 1 wherein in step (iii), the pressure inside said glass mother tube is 1 - 30 mm H 2 0 lower than the pressure outside the tube.
Claim 4
Dependent Claim
30 words
A method as defined in claim 1 or claim 2 wherein in the step (iii), the glass mother tube is heated to a temperature in the range 1700°C - 2000°C.
Claim 5
Independent Claim
29 words
A method as defined in any one of claims 1 to 3 wherein the glass mother tube is heated to decrease its diameter between step (i) and step (ii).
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