Sumitomo Electric Industries, Limited

Yuichi Ohga

Shinji Ishikawa

Toshio Danzuka

Motonori Nakamura

Hiroshi Yokota

Hiroo Kanamori

Ichiro Tsuchiya

Tadashi Enomoto

Sumio Hoshino

Masumi Ito

Michihisa Kyoto

Katsuya Nagayama

Eiji Yanada

Toshihiro Ooishi

Eisuke Sasaoka

Masashi Onishi

Haruhiko Aikawa

Tatsuhiko Saito

Masao Tsukitani

Tatsuhiko Saitoh

Yoshio Yokoyama

Takashi Kogo

Osamu Kasuu

Katsuzo Mukai

Nobuya Akaike

Takashi Matsuo

Atsushi Inoue

Masaaki Hirano

Masayuki Nishimura

Motoki Kakui

Takashi Yamazaki

Masakazu Shigehara

Tomohiro Ishihara

Kohei Kobayashi

Satoshi Tanaka

Daisuke Yokota

Kazuya Kuwahara

Koji Nakazato

Masahiro Takagi

Shinji Endo

Masahide Saito

Ichiro Yoshimura

Toru Adachi

Tatsuo Saito

Toshihiro Ohishi

Hiroshi Takamizawa

Takenori Uchiyama

Kouji Amemiya

Horoshi Yokota

Kouji Takata

Hikaru Sato

Ichiro Tuchiya

Shuichiro Kato

Susumu Uchida

A core rod is inserted into a cladding pipe, moisture in a space between the core rod and the cladding pipe is removed, and an optical fiber is drawn while the space is connected to a dry-gas atmosphere and/or being decompressed and while the core rod and the cladding pipe are being unified with each other. Alternatively, the core rod is inserted into the cladding pipe, and an optical fiber is drawn from one end while moisture on the surface of the core rod and the internal surface of the cladding pipe is being removed. Accordingly, a high quality optical fiber is manufactured with good productivity.

Optical fiber and manufacturing method thereof

A dispersion compensating optical fiber comprises a minimum wavelength at which an increase amount of an actual loss value with respect to a theoretical loss value is not less than 10 mdB/km in a use wavelength band and on a long wavelength side of the use wavelength band. The actual loss value is measured in a state that the fiber is looped around a bobbin. The minimum wavelength falls within a range of 1,565 to 1,700 nm. This dispersion compensating optical fiber is suitably used for an optical transmission line of a large-capacity high-speed WDM optical transmission system.

Dispersion compensating optical fiber, dispersion compensating device, optical transmission line and optical transmission system

A concentric multi-tubular burner for synthesizing glass particles having a center port group constituted by a combination of jet ports of raw material gas, combustible gas and oxygen gas, wherein an outer wall of the oxygen gas jet port in the center port group protrudes more toward a burner head than an inner wall of the oxygen gas jet port. The flow rate of oxygen gas jetted from the oxygen gas jet port of the center port group is controlled to be in a proper range.

Burner for synthesizing glass particles and method for producing porous glass body

A drawing apparatuscomprises a drawing furnace, a protecting tube, and a resin curing unit. A buffer chamberis disposed between the drawing furnaceand the protecting tube, and has a length Lin the drawing direction of the optical fiber. The buffer chamberis constituted by a first buffer celland a second buffer cell. In the space within the buffer chamber, an He gas, which is an atmosphere gas within the drawing furnace, and the air, which is an atmosphere gas within the protecting tube, exist in a mixed state. The optical fiberdrawn upon heating in the drawing furnaceis fed to the protecting tube, and a predetermined part of the optical fiberis annealed at a predetermined cooling rate. Thereafter, a coating diecoats the optical fiberwith a UV resin solution, and the resin curing unitcures the UV resin, whereby a coated optical fiberis obtained.

Optical fiber producing method

A plurality of glass particles synthesizing burners are arranged at a predetermined burner interval opposite to a rotating starting rod. The starting rod and the glass particles synthesizing burners are relatively parallely reciprocally moved, and the soot deposition is conducted. A reciprocating speed v(mm/minute), axis rotating speed r (rpm), and burner interval L (mm) are set so that a value A expressed by the expression A=(r/v)&#xd7;L is in a range 40&#x2267;A&#x2267;8.

Method of producing optical fiber preform

A method for producing an optical fiber preform is provided in which the variation of the outer diameter in the longitudinal direction is minimized and a target quantity of glass is accumulated as a whole. Based on a predetermined relationship between three variables: the outer diameter of a starting rod being a first variable, the outer diameter of an optical fiber preform a second variable, and the timing for ending the glass particles depositing process a third variable, the starting rod and burners are subjected to relative reciprocating movement so as to deposit glass particles on the starting rod until the timing for ending the depositing process, and then the resulting deposit body is vitrified. The third variable may be the traverse velocity, the glass particles deposition time, or the weight of a soot glass deposit body.

Method of manufacturing optical fiber preform

A drawing apparatushas a drawing furnace, a heating furnace, and a resin curing section. The drawing furnacehas a muffle tubeto which an He gas supply passagefrom an He gas supply sectionis connected so as to supply He gas. The optical fiberdrawn upon heating by the drawing furnaceis fed to the heating furnace, whereby a predetermined part of the optical fiberis annealed at a predetermined cooling rate. The heating furnacehas a muffle tubeto which an Ngas supply passagefrom an Ngas supply sectionis connected so as to supply Ngas. Thereafter, the optical fiberis coated with a UV resinby a coating die, and the UV resinis cured in the resin curing section, whereby a coated optical fiberis formed.

Apparatus and method for making optical fiber

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

Three or more glass particle synthesizing burners are arranged to be opposed to a rotating glass rod. The glass rod and the glass particle synthesizing burners are reciprocated in parallel and relatively to deposit glass particles synthesized by the burners on the surface of the glass rod, thereby producing a soot body. The glass particle synthesizing conditions of the burners arranged at both ends are changed to have a greater deposition amount of glass particles per unit time in part or all of its movement range than other burners.

Method for producing soot body

A process for producing fluorine-containing glass. An SiO soot is synthesized by hydrolyzing SiCl . The soot is heated in a chlorine-compound-free atmosphere containing a fluorine compound gas to form a fluorine-containing silica glass. The glass contains not more than 10 ppm OH group, not more than 10 ppm Cl, and not less than 1,000 ppm F. The concentration ratio of F/Cl is 10,000 or more.

Fluorine-containing glass

A plurality of glass particle synthesizing burners are disposed opposite to a rotating starting rod. The starting rod and the glass particle synthesizing burners are relatively reciprocally moved to each other in parallel to the axial direction, so that glass particles synthesized by the burners are sequentially deposited on the surface of the starting rod. The movement is stopped and restarted repeatedly once or more than once during one reciprocal movement.

Method of producing glass particles deposit

An optical fiber splicing method capable of fully reducing the splice loss at room temperature is provided. In the optical fiber splicing method in accordance with the present invention, respective end faces of optical fibers are fused together in a splicing step (S ). In a condition setting step (S ), a set value &agr; is set. Thereafter, a heating step (S ), a measuring step (S ), and a termination determining step (S ) are carried out repeatedly. In the heating step, a region including the fusion-spliced point is heated under a predetermined heating condition. In the measuring step, splice loss is measured. In the termination determining step, the splice loss &agr; measured in the measuring step and the set value &agr; set in the condition setting step are compared with each other in terms of magnitude. If the splice loss &agr; is not greater than the set value &agr; , then it is determined that the alternation should be terminated, whereby the optical fiber connecting operation is terminated.

Optical fiber splicing method and optical fiber

Two optical fibers to be spliced are prepared, coatings of resin are removed from end portions of the respective optical fibers to expose glass fibers, the glass fibers are aligned to each other, an a fusion step is carried out to heat the end faces of the glass fibers to cause fusion thereof to form a fusion-spliced portion. After that, an additive-diffusing step is carried out to diffuse an additive added in the glass fibers around the fusion-spiced portion, by a heat treatment around the fusion-spliced portion, by a heat treatment around the fusion-spliced portion at a first temperature of not less than 800&deg; C. nor more than 1500&deg; C. Further after the additive-diffusing step, a thermal-strain-removing step is carried out to remove thermal strain by a heat treatment of a wider region than heated regions in the fusion splice step and in the additive-diffusing step of the fusion-spliced portion, at a temperature of not less than 500&deg; C. nor more than 1200&deg; C.

Method of splicing two optical fibers

The present invention relates to an OFA having a high signal gain, easily manufactured, having a high mechanical strength, having a small splice loss with respect to other optical fibers, and rarely encountering the occurrence of noise at a signal wavelength. The OFA according to the present invention has a function of amplifying signals propagating therethroug by pumping light supplied thereto, and comprises, at least, a core region, an inner cladding region provided on the periphery of the core region, an outer cladding region provided on the periphery of the inner cladding region, and one or more node coupling gratings. An element for signal amplification is added to at least the core region. The core region has a structure ensuring a core mode with respect to the signals, while the inner cladding region has a structure ensuring a multi-mode with respect to the pumping light. Each of the mode coupling gratings passes core mode signals therethrough, and induces a mode coupling between the inner cladding mode and the core mode with respect to the pumping light.

Optical fiber for optical amplifier, optical fiber amplifier and optical fiber laser

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Yokohama, Japan

Yuichi Ohga