| 摘要 |
1490700 Optical fibre preform STANDARD TELEPHONES & CABLES Ltd 10 Dec 1974 [20 Dec 1973] 59168/73 Heading ClM An optical fibre preform is made from silica substantially uniformly doped with an oxide dopant selected from GeO 2 , Sb 2 O 3 and Ga 2 O 3 or mixtures thereof, which dopant oxide increases the refractive index of the silica and will diffuse out of the silica on heating, by heating a rod of the doped silica to 1200‹ C. under conditions such that some of the oxide dopant is driven off, to provide a surface region of reduced refractive index. The rod may be treated as it is pulled from a melt of the doped silica. The glass rod (e.g. of 80% by weight SiO 2 and 20% by weight GeO 2 ) may be heated to 1200‹ C. for “-1 minute so that the dopant is depleted to a depth of about 50 microns. |
