METHOD OF DRAWING BARE OPTICAL FIBER, PROCESS FOR PRODUCING OPTICAL FIBER STRAND AND OPTICAL FIBER STRAND

摘要

A drawing method for a bare optical fiber, comprises the steps of: melting an optical fiber preform using a heating device and drawing the bare optical fiber; and naturally cooling down the bare optical fiber or forcibly cooling down the bare optical fiber by a cooling device after the heating and melting step, wherein a temperature history during the drawing the optical fiber preform to obtain the bare optical fiber in the heating device satisfies a relational expression: T ‰¤ -0.01X + 12 where a time period when the heated and molten portion of the optical fiber preform heated and molten by the heating device reaches 1800°C or higher is T (min) and a OH group concentration in a cladding layer of the optical fiber preform is X (wtppm).