Method for producing glass preform for optical fiber

Abstract

A method for producing a glass preform for an optical fiber comprising jetting SiCl.sub.4 as a glass-forming raw material and an insert gas from a first nozzle of a multi-nozzle burner and, as another glass-forming raw material, at least one hydrogen-containing silicon compound with larger oxidation or hydrolysis reaction heat than that of SiCl.sub.4 selected from the group consisting of SiHCl.sub.3, SiH.sub.2 Cl.sub.2, SiH.sub.3 Cl and SiH.sub.4 from a second nozzle surrounding the first nozzle, flame hydrolyzing or oxidizing the glass-forming raw materials to synthesize glass soot particles, depositing the glass soot particles on a starting member to form a porous soot preform with a controlled bulk density distribution and heating and sintering the soot preform to obtain a transparent glass preform, by which a large glass preform is stably produced without cracking.

Dependencies are inferred from the claim text.