| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To manufacture an optical fiber preform having high yield of a dopant and little local fluctuation of the refractive index when the optical fiber preform is produced by synthesizing soot by an outer deposition method (OVD). <P>SOLUTION: When the soot 130 in a segment layer is synthesized on a start preform 120 by adding a dopant to increase the refractive index, e.g. germanium tetrachloride (GeCl<SB>4</SB>), and glass source material gas (SiCl<SB>4</SB>) to a burner, hydrolyzing the material by flames of the burner and blowing GeO<SB>2</SB>and SiO<SB>2</SB>to the start preform, the synthesis of the soot is carried out while keeping the density of the soot to a proper value, for example,≤0.4 g/cm<SP>3</SP>and preferably to 0.1 to 0.3 g/cm<SP>3</SP>or lower and keeping the temperature of the deposition surface of the soot 130 to a specified temperature, for example, to 300 to 600°C, preferably to 350 to 580°C. <P>COPYRIGHT: (C)2003,JPO</p> |
