OPTICAL FIBER PRODUCTION METHOD AND PRODUCTION DEVICE, AND OPTICAL FIBER

摘要

The present invention provides a method and an apparatus for producing an optical fiber in which the increase in transmission loss is reduced while the variation in the diameter of a glass fiber is suppressed using an inexpensive inert gas or the like and inexpensive auxiliary devices, and provides an optical fiber to be produced using the method and the apparatus. The apparatus is equipped with a susceptor (13) into which an optical fiber preform (11) is inserted and a heater (15) disposed outside the susceptor to heat the susceptor from the outside and produces an optical fiber by drawing a glass fiber (12) while the optical fiber preform is heated and melted and by drawing out the fiber through the outlet at the lower section of the susceptor to the outside. A gas containing 50% or more of argon or nitrogen is used as a gas to be supplied into the susceptor, and a protective pipe (17) with a length of Da (mm) is provided under the susceptor, the protective pipe having a heat insulating region (17a) enclosed with a heat insulator (18) with a length of Db (mm) at the upper section thereof and a non-heat insulating region (17b) not enclosed with any heat insulators at the lower section thereof, and settings are made so that the temperature of the glass fiber at the outlet of the protective pipe becomes 1700°C or less and so that the outer diameter of the glass fiber at the outlet of the protective pipe is within a range of the target outer diameter of the glass fiber + 6 µm or less.