| 摘要 |
PURPOSE:A clear glass rod is fibre-polished with a flame which is prepared by introducing an etching gas into a combustion gas free hydrogen, then soot is deposited whereby the title parent material with substantially reduced trans mission loss caused by hydroxyl groups is obtained. CONSTITUTION:The cylindrical center 10 of a clear glass is to be the core for optical fiber and is composed of, e.g., Ge-doped silica or a silica doped with a slight amount of F. Or the center material 10 is composed of the core 12 and the clad 14. The surface of the center material 10 is fire-polished with a flame 32 of a combustion gas free from hydrogen. At the same time, an etching gas 30 is introduced into the flame 32 to each the surface of the center material 10. Then, soot 20 is deposited on the surface, the soot is heated into a wholly clear glass rod (preform). When needed, the deposition of the soot and the heating of the deposited soot are repeated to prepare the objective parent material. |
