| 摘要 |
PURPOSE:To obtain an optical fiber which evades stress concentration and has a superior transmission band by adding an additive which compensates the difference in coefficient of linear expansion between a core and a clad to the clad together with fluorine. CONSTITUTION:A material to be added to the clad itself is selected to compensate the difference in coefficient of linear expansion between the core and clad, and thus stress concentration on the interface is reduced; and the coefficient of linear expansion of quartz glass to which fluorine is added is smaller than that of pure quartz glass. For the purpose, another additive is added to the clad together with the fluorine to approximate the coefficient of linear expansion to that of the pure quartz glass, reducing the stress concentration. Consequently, the additive which increases the coefficient of linear expansion of the clad is necessary. When the additive has such property that the refractive index is increased, the increase in refractive index is preferably small. In this case, P2O5 approximates the coefficient of linear expansion to that of the pure quartz glass without causing any deterioration in light transmission loss, so P2O5 and fluorine are added as additive to the clad. |
