| 摘要 |
<p>Rare earth or other metallic elements, eg Nd and Er, are introduced into optical glass fibre for telecommunications by evaporating a suitable salt, eg NdCl3 or ErCl3, 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.</p> |
