| 摘要 |
In the process of the principal patent, the inner wall of a glass tube is covered by at least one glass layer of higher refractive index than that of the tube, forming the core of the optical fibre. In the present process, the coating of the inner wall of a glass tube of silicon dioxide (11) is carried out by applying a dopant layer (10) which is converted, under the action of heat, into a glass layer of higher refractive index than that of the tube. The dopant used is preferably an oxide of one or more of the elements germanium, aluminium, titanium, arsenic, gallium, phosphorus, antimony, tantalum, tin, niobium, indium and zirconium, the coating material being deposited by a reaction in which hydrogen and compounds thereof are excluded.
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