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

摘要

A method of drawing a bare optical fiber, comprising the step of melting an optical fiber parent material by heating means and drawing a bare optical fiber and the step of after the heat melting step, subjecting the bare optical fiber to natural cooling or forced cooling with cooling means, wherein in the heat melting step, the temperature history during drawing of the optical fiber parent material into the bare optical fiber with the use of the heating means satisfies the relationship of the formula T ≤ -0.01X + 12 wherein T represents the time (min) during which the portion of optical fiber parent material thermally molten by the heating means reaches 1800°C or higher and wherein X represents the concentration (wtppm) of OH groups in a clad layer of the optical fiber parent material.