OPTICAL FIBER Russian patent published in 1995 - IPC

FIELD: production of optical fibers. SUBSTANCE: glass which contains (mass %): SiO₂ 37,0-48,2; CaO 0.3-3.8, ZnO 8.3-16.6, BaO 0.9-15.7, Li₂O 0,1-1,2; Na₂O 4,9-6,3; K₂O 7,4-9,6; As₂O₃ or CeO₂ 0,3-0,5 and at least one of the following oxides TiO₂, GeO₂, PbO, Nb₂O₅ 8,7-26,8 is used for core. Glass envelope contains (mass %): SiO₂ 56,8-61,7; B₂O₃ 14,4-17,3 MgO 6.5-8.3, Li₂O 0,1-1,5; Na₂O 6,1-7,5; K₂O 9,3-11,3; As₂O₃ or CeO₂ 0,3-0,5, Boiling temperature of said glass is (1250-1320 )± 20 C. Refractive index for core and for envelope is 1.577-1.634 and 1.517-1.523 respectively. EFFECT: increases transmission, decreases boiling temperature. 2 tbl