| 摘要 |
PURPOSE:To prepare an optical fiber preform rod having excellent characteristics and composed of a core layer and a clad layer, by forming a porous glass preform containing metal oxide for the regulation of refractive index, and heating the preform in the atmosphere of a halogen gas and a reducing gas. CONSTITUTION:A raw material gas which forms the deposition of fine glass powder containing metal oxide for regulating refractive index by the thermoxidation reaction or hydrolysis, e.g. a raw material gas consisting of SiCl4, POCl3, GeCl4, H2 and O2, is supplied to a multilayered burner, and the porous glass preform 1 forming the core layer is formed by the VAD process using flame hydrolysis. The preform 1 thus obtained is put into the electric oven 2, and heat-treated under the flow of a halogen gas and a reducing gas, e.g. Cl2 gas and He gas. The consolidated optical fiber glass preform is elongated to obtain an optical fiber having a core layer and a clad layer. |
