Patent ID: 6907757
Filing Date: 2005-06-21
Classification: C03B,Y02P

Abstract:
1. A drawing method of optical fibers using a drawing furnace comprising a furnace muffle tube into which an optical fiber preform is inserted, a furnace body surrounding said furnace muffle tube, and a heater positioned inside said furnace body and peripheral to said furnace muffle tube, said method comprising steps of: inserting said optical fiber preform from the inlet of said furnace muffle tube; heating and melting said optical fiber preform by means of said heater under a specified gas atmosphere; and drawing an optical fiber toward the outlet of said furnace muffle tube with a specified drawing tension; wherein said optical fiber preform and said drawing furnace used in said drawing method satisfy the condition of below-indicated Formula (1): where, in Formula 1, L means the length [mm] of the furnace body in the drawing direction and D means the diameter [mm] of the optical fiber preform, and said optical fiber preform used in the drawing method has a relative index difference of 1% or greater between the center core and the cladding thereof.