| 摘要 |
PURPOSE:To obtain an optical fiber preform having low transmission loss, by depositing glass soot on a starting member and heat-treating the obtained preform while varying the concentration of the halogen-containing gas in the atmosphere according to the heat-treatment temperature. CONSTITUTION:Glass soot is deposited on the outer circumference or the tip of a starting member by CVD reaction, etc., to form a porous glass preform. The preform is made transparent by heating in a halogen-containing gas atmosphere. In the above process, the concentration of the halogen-containing gas is varied according to the heat-treatment temperature to keep the halogen concentration diffused into the preform and uniformize the refractive index. |
