Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Takashi Kogo

Masashi Onishi

Hiroo Kanamori

Yuichi Ohga

Masataka Nakazawa

Yoshiaki Miyajima

Takashi Yamazaki

Yoichi Ishiguro

Tadashi Enomoto

Yutaka Katsuyama

Masaharu Ooe

A dehydration and consolidation furnace and a dehydration and consolidation method in which gas in a chamber does not leak to a furnace body room and gas in a furnace body room does not leak into a chamber is provided. A furnace of one embodiment of this invention has first muffle tubeand second muffle tube. The second muffle tubeis arranged coaxially around the first muffle tube. An optical fiber preform is arranged in this furnace. During the dehydration and consolidation process the pressure of the intermediate roomis set lower than a pressure inside the first muffle tube and outside the second muffle tube, and a gas supply and exhaust of the intermediate roomare performed independent of the gas supply and exhaust of the first muffle tube and a furnace body room.

Apparatus for dehydrating and consolidating an optical fiber preform and method of the same

The object of the invention is to provide an apparatus for manufacturing a porous glass preform, which comprises a reaction vessel in which local stress concentration caused by expansion due to heat is prevented, and there is no fear of the occurrence of deformation or cracks. The apparatus of this invention manufactures the porous glass preform by depositing glass particles blown from a burner on the seed rod rotating around its axis, and this apparatus is characterized in that the reaction vessel is provided with a means for relieving concentration of stress due to thermal expansion of the reaction vessel.

Apparatus for manufacturing porous glass preform

Lead-containing fluoride glass comprises 50-70 mol % of ZrF.sub.4, 3-5 mol % of LaF.sub.3, 0.1-3 mol % of YF.sub.3, and 2-15 mol % of NaF and/or LiF and/or CsF, where LaF.sub.3 +YF.sub.3 =4.5-6 mol %, and further comprises lead. An optical fiber comprises a core made of the lead-containing fluoride glass and a cladding surrounding the core. A process for producing an optical fiber comprises forming a base material for a core of the lead-containing fluoride glass, forming a base material for a cladding of fluoride glass containing 30-60 mol % of HfF.sub.4, and drawing the base materials into an optical fiber at a drawing temperature of 315-340 .degree. C.

Lead-containing fluoride glass, optical fiber and process for producing

Lead-containing fluoride glass comprises 50-70 mol % of ZrF.sub.4, 3-5 mol % of LaF.sub.3, 0.1-3 mol % of YF.sub.3, and 2-15 mol % of NaF and/or LiF and/or CsF, where LaF.sub.3 +YF.sub.3 =4.5-6 mol %, and further comprises lead. An optical fiber comprises a core made of the lead-containing fluoride glass and a cladding surrounding the core. A process for producing an optical fiber comprises forming a base material for a core of the lead-containing fluoride glass, forming a base material for a cladding of fluoride glass containing 30-60 mol % of HfF.sub.4, and drawing the base materials into an optical fiber at a drawing temperature of 315.degree.-340.degree. C.

The invention relates to an optical fiber in which an optically functioning element is doped in at least the core, and the cladding is hermetically coated with carbon film and an optical fiber-type optically active device comprising: an optical fiber loop bundle constituted by a plurality of winds of an optical fiber hermetically coated with carbon and doped with an optionally functioning element; and beam introducing means for introducing a beam for pumping the optically functioning element into the optical fiber loop bundle.

Growing community of inventors

Yokohama, Japan

Takashi Kogo