Manufacturing method thereof of an optical fibre

摘要

Provided is an optical fiber having holes extending along the axis whose transmission loss is substantially reduced and the manufacturing method thereof. First, a plurality of through-holes 9 are formed in a preform 5 extending along the preform axis. Subsequently, the preform 5 is heated by heating means 24 in the furnace preferably for 30 minutes or more at a temperature equal to or more than 800 DEG C while flowing a dry gas in the through-holes 9. As a result, the OH group which exists on the surfaces of the inner walls 5a of the through-holes 9 of the preform 5 is discharged outside the preform. Subsequently, the preform 5 is drawn into an optical fiber.