초록 ▼

A core torch for fabricating a single-mode optical fiber preform wherein fine glass particles are produced eccentrically with respect to the center area of a flame stream, the core torch being so arranged as to blow the flame stream at an angle inclined to a seed rod. The porous glass body forming t

A core torch for fabricating a single-mode optical fiber preform wherein fine glass particles are produced eccentrically with respect to the center area of a flame stream, the core torch being so arranged as to blow the flame stream at an angle inclined to a seed rod. The porous glass body forming the core is grown on one end of the rod and in the direction of the axis of the rod. A cladding layer is formed on the periphery of the porous glass core body by at least one torch for forming the cladding. The obtained porous glass body is heated and vitrified into a transparent glass body, which is sealed in a silica tube for jacketting to form a single-mode optical fiber preform. At least one exhaust port is disposed within a distance of 1 mm to 50 mm from the periphery of the porous glass body and in the vicinity of the growing surface of the glass body to exhaust residual glass fine particles and undesired gases. A porous glass body having a diameter of 20 mm or less is easily formed. Single-mode optical fiber having a cladding-to-core-diameter ratio of 3 or more is fabricated by the VAD method. Accordingly, a long-length and low-loss single-mode optical fiber is mass-produced.

대표청구항 ▼

A torch for fabricating a porous preform for a core used in fabricating single-mode optical fibers, said torch comprising a glass raw material gas blowing nozzle and a combustible gas blowing nozzle, said combustible gas blowing nozzle surrounding said glass raw material gas blowing nozzle in such a

A torch for fabricating a porous preform for a core used in fabricating single-mode optical fibers, said torch comprising a glass raw material gas blowing nozzle and a combustible gas blowing nozzle, said combustible gas blowing nozzle surrounding said glass raw material gas blowing nozzle in such a manner that a glass raw material gas blown out from said glass raw material gas blowing nozzle is deviated from the center of an inner area defined by said combustible gas blowing nozzle, with respect to an oxy-hydrogen flame stream blown out from said combustible gas blowing nozzle.