OPTICAL GLASS AS CORE GLASS FOR A FIBRE-OPTIC LIGHT GUIDE AND FIBRE-OPTIC STEPPED-INDEX FIBRE WITH THIS CORE GLASS

摘要

A description is given of a novel optical glass as a core glass for a fibre-optic light guide, which glass has a composition (in mol% on an oxide basis) of 50 - 60 SiO2, 0 - 15 B2O3, 10 - 35 BaO, 0 - 18 SrO, 10 - 35 ∑ SrO + BaO, 0 - 15 ZnO, 10 - 40 ∑ SrO, BaO + ZnO, 5 - 35 ∑ B2O3 + ZnO, 0.1 - 1.9 Al2O3, 0 - 4 ZrO2, 0 - 4 La2O3, 0 - 4 Y2O3, 0 - 4 Nb2O5, 0 - 4 ∑ La2O3 + Y2O3 + Nb2O5, 4.5 - 10 Na2O, 0.1 - 1 K2O, 0 - 1.5 Rb2O, 0 - 1.5 Cs2O, 0 - 1.5 ∑ Rb2O + Cs2O, 4.8 - 11 ∑ alkali oxides, 0 - 6 MgO, 0 - 5 CaO. Furthermore, an optical stepped fibre comprising the core glass described and a cladding of boron-containing silicate glass is described, wherein the cladding glass has a refractive index nd which is at least 2% lower than that of the core glass and wherein the cladding glass has a viscosity which is equal to or preferably greater than the viscosity of the core glass at the temperature of fibre production and has a coefficient of linear thermal expansion s which is equal to or in particular at least 2 × 10-6 K-1 less than that of the core glass.