| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an optical fiber preform at a reduced manufacturing cost by making the large-size optical fiber preform without using expensive helium gas. SOLUTION: The method comprises the porous preform layer formation step S1 of forming a porous preform layer 9C by depositing glass microparticles around the circumference of a core rod 7A having a core layer 3A, the dehydration step S2 of dehydrating the porous preform layer 9C under at least one condition of a vacuum, an inert gas/halogen gas atmosphere, and an inert gas/halogen compound gas atmosphere, the sintering step S3 of sintering the dehydrated porous glass preform layer 9C in a vacuum into a translucent glass preform layer 9B containing closed cells, and the transparentization step S4 of transparentizing the translucent glass preform layer 9B containing the closed cells in an inert gas (except helium gas) atmosphere into a clad layer 9A. COPYRIGHT: (C)2006,JPO&NCIPI |
