| 摘要 |
PURPOSE:To manufacture an optical fiber preform having high quality, economically, by applying a porous gel such as silicon alcoholate to the surface of the rod-shaped transparent preform for the core, and heat-treating the product to convert the gel to transparent clad. CONSTITUTION:The raw material 3 for forming a clad (a sol solution of a silicon alcoholate prepared by dissolving ethyl silicate in an alcohol and adding a proper amount of water to the solution) is poured into the vessel 2, and a rod-shaped transparent preform 1 for the core synthesized by VAD process, etc. is immersed vertically in the raw material 3. The vessel is heated slowly to about 110 deg.C to effect the hydrolysis of the sol. The raw material is converted from sol to gel, and then released from the wall of the vessel to obtain the preform 1 coated with dry (porous) gel. The product is heat-treated at about 1,300 deg.C in He+Cl2 atmosphere to obtain a transparent optical fiber preform composed of a core and a clad. A dispersion of fumed silica may be used as the raw material 1. |
