| 摘要 |
PURPOSE:To improve deposition efficiency of glass fine particles on porous optical fiber preform and production yield in producing porous optical fiber preform by VAD method by depositing glass fine particles while blowing a low-temperature gas on the surface of porous optical fiber preform by a specific method. CONSTITUTION:In a method of producing a porous optical fiber preform 6 by feeding glass raw materials and a combustion gas to a burner 1, subjecting to flame hydrolysis reaction and depositing formed glass fine particles 2 on the surface of starting raw materials, the following constitution is added. Namely, at a position opposing the burner 1 laid between the porous optical fiber preform 6 and the burner, a low-temperature gas 8 (nozzle 7) is sprayed upon the surface of the porous optical fiber preform 6 so that the glass fine particles 2 are deposited while being cooled. He, N2, Ar, air or CO2 is preferable as the low-temperature gas. |
