| 摘要 |
PURPOSE:To improve the weather-resisting property, to prevent glass fibers from becoming opaque during working and to improve the sizing stability and charactristics during drawing by using preset multi-component glass materials as materials for a core and a cladding. CONSTITUTION:Multi-component glass A for a core, which contains in wt. percent 35 to 65 % of SiO2, 10 to 23 % of osides of alkaline metal and the remainder of 15 to 50 % of the sum of CaO, BaO and ZnO, and multi-component glass B for a cladding, which contains 65 to 80 % of SiO2, 0.5 to 10 % of Al2O3, 9 to 17 % of oxides of alkaline metal, 1 to 5 % of CaO, 0 to 4 % of MgO and 0 to 10 % of B2O3, are drawn by the dual-crusible method to produce step type multi-component glass fibers for optical communication. As a result, the difference in thermal expansion coefficient between the glass materials A and B is smaller than 3 X 10<-6> cm/cm deg.C at a temperature of 0 to 300 deg.C, and the difference in specific refractive index inbetween is higher then 0.015, as defined by DELTAn=(n1 - n2)/n1 (wherein n1 stands for the refractive index of the core; and n2 stands for the refractive index of the cladding). |
