Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Public Corporation

Kazunori Chida

Minoru Watanabe

Hiroshi Yokota

Hiroo Kanamori

Michihisa Kyoto

Gotaro Tanaka

Naoki Yoshioka

Hisao Sato

An improved process for the production of optical fiber porous preforms of predetermined refractive index distribution by the vapor-phase deposition method is disclosed wherein a glass material and a dopant material are subjected to flame oxidation by the use of an oxyhydrogen burner to form fine glass particles which are deposited on one end of a supporting rod adapted to move apart from the oxyhydrogen burner while rotating to allow a rod-like porous preform to grow thereon. The improved process is characterized in that the correlation between the shape of the deposition face and the refractive index distribution is previously determined mathematically, and on a basis of the correlation therebetween, a process variable such as the distance between the porous preform and the burner is adjusted to produce the desired shape of the deposition face whereby there can be obtained an optimum refractive index distribution.

Process for the production of optical fiber preforms

A method for producing an optical fiber preform comprising injecting a glass raw material, a gaseous fluorine-containing material and oxygen gas from a first nozzle, inactive gas from a second nozzle which surrounds the first nozzle and hydrogen gas from a third nozzle which surrounds the second nozzle, flame hydrolyzing the glass raw material to synthesis fine glass particles and depositing the fine glass particles on a tip of a rotating seed rod to produce the optical fiber preform containing fluorine.

Method for producing optical fiber preform

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Mito, Japan

Kazunori Chida