| 摘要 |
The drawing method of the present invention uses a drawing furnace comprising a furnace muffle tube, a furnace body and a heater. According to the method, an optical fiber preform is inserted from the inlet of the furnace muffle tube, the optical fiber preform is melted by means of a heater, under a specified gas atmosphere, and is drawn toward the outlet of the furnace muffle tube by means of a specified drawing tension. The optical fiber preform and the drawing furnace used in this method both satisfy the condition of below-indicated formula (1): <?in-line-formulae description="In-line Formulae" end="lead"?>L/D>=8 (1) <?in-line-formulae description="In-line Formulae" end="tail"?> wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform. Through this method, even for the case of drawing optical fibers having a large relative index difference between the central core and the cladding, optical fibers wherein residual amounts of lattice defects are sufficiently reduced and degradation of characteristics under a hydrogen atmosphere is sufficiently suppressed can be obtained efficiently and at low cost.
|
