OPTICAL FIBRE TRANSMISSION LINE

摘要

The core (1) may be pure or doped SiO2 whereas the sleeve (2) can be doped to a constant value or in steps so its refractive index decreases towards the periphery of the sleeve, this decrease towards the periphery of the sleeve may also be parabolic. The fibre is pref. drawn from a tubular blank coated in the bore with a layer (2) of SiO2 contg. F2, followed by a layer (1) of SiO2 forming the core after drawing. Hitherto only one element, boron, has been used to lower the refractive index of SiO2, and the actual value depends on the thermal history of the fused silica. When F2 is used as the dopant, the value depends only on the amt. of F2.