PRODUCTION OF OPTICAL FIBER PREFORM

摘要

PURPOSE:To improve the yield of raw material gas in the production of an optical fiber preform, by ejecting raw material gas and combustion gas through a multiple tube burner keeping the flow rate of the glass raw material gas and that of adjacent combustion gas at a specific ratio and hydrolyzing the raw material gas. CONSTITUTION:A rotatable and vertically movable core rod 2 is inserted into a reaction vessel 1 and a porous glass preform 3 for the production of optical fiber is formed by vapor-phase axial deposition using a multiple tube burner 4. In the above process, SiCl4 gas as a raw material for glass is flowed through the 1st port positioned at the center of the burner 4 at a flow rate of 3l/min, H2 gas through the adjacent 2nd port at a rate of 1-30l/min, Ar gas through the 3rd port at a rate of 3l/min and O2 gas through the outermost 4th port at a rate of 15l/min. A porous glass preform 3 can be produced in high yield of SiCl4 by adjusting the flow rate of the sintering gas H2 passing through a layer adjacent to the raw material layer to 1-4 times the flow rate of the raw material layer of a multiple tube burner forming a plurality of flame planes.