To provide a method for producing an erbium-containing porous preform for an optical fiber capable of stably producing an optical fiber preform having a uniform required concentration of aluminum without generating bubbles and to provide a method for producing an erbium-containing optical fiber preform.
In the early stage of deposition of fine glass particles, the deposition temperature of fine glass particles is regulated to ≤1,200°C and gaseous SiCl4 and gaseous AlCl3 are supplied to a burner for synthesis of glass. The flow rate of oxyhydrogen is then adjusted, and after the temperature of fine glass particles attains to ≤850°C, gaseous GeCl4 is further supplied. An erbium- containing porous preform for an optical fiber is temporarily sintered at 850-1,200°C to impart 0.6-1.2 g/cm3 bulk density to the temporarily sintered preform.
NAKAYAMA SHINICHI
HARADA KOICHI
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