| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method of an optical fiber preform which enables selective addition of fluorine (element F) to prescribed restricted part. SOLUTION: This production comprises: a step S1 for preparing a porous preform contg. a prescribed additive added to a prescribed part of a quartz base material of the preform; a step S2 , i.e., a dehydration stage for removing adsorbed water from this porous preform; a step S3 , i.e., a heating stage for subjecting the dehydrated porous preform to heat treatment at 1,350 to 1,440 deg.C to increase the bulk density of the prescribed part; a step S4 , i.e., a fluorine addition stage for adding fluorine (element F) to the part of treated porous preform other than the prescribed part; and a step S5 , i.e., a sintering stage for sintering the resulting porous preform to produce the objective optical fiber preform. |
