| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for effectively removing moisture and hydroxy groups (OH) present at an interface or preventing foreign matters from attaching to the surface when manufacturing an optical fiber preform having at least one interface between neighboring soot inside a mode field, wherein the neighboring silica glass bodies are individually prepared through different processes. SOLUTION: Before synthesizing the soot, the interface part is subjected to dry etching using a halogen gas such as a fluorine (F)-containing gas such as SiF<SB>4</SB>, Si<SB>2</SB>F<SB>6</SB>, CF<SB>4</SB>and C<SB>2</SB>F<SB>6</SB>. For dry etching, e.g. (CO+O<SB>2</SB>) flame or flame containing an etching gas and no hydrogen nor moisture in its center is used. COPYRIGHT: (C)2004,JPO |
