Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Sumitomo Electric Industries, Co.

Katsuya Nagayama

Kazuya Kuwahara

Ichiro Tsuchiya

Ichiro Yoshimura

Haruhiko Aikawa

Masashi Onishi

Yuichi Ohga

Yoichi Ishiguro

Toshifumi Hosoya

Toshiki Taru

Nobuyuki Yoshizawa

Yutaka Katsuyama

Eisuke Sasaoka

Takatoshi Kato

Yasuo Matsuda

Kaoru Okuno

Katsuyuki Tsuneishi

Tatsuhiko Saitoh

Kiichiro Kawasaki

Masayuki Nishimura

Shinji Ishikawa

Yuji Kobayashi

Yutaka Wada

Toshio Danzuka

Kohei Kobayashi

Takayuki Shimazu

Tatsuhiko Saito

Hiroaki Ohta

Motohide Yoshida

Hiroshi Takamizawa

Masao Koida

Takenori Uchiyama

The method of manufacturing an optical fiber in accordance with the present invention comprises a step of yielding an optical fiber by drawing an optical fiber preform softened upon heating, wherein a temperature at which the optical fiber preform is softened is at least 1800&#xb0; C., whereas the optical fiber preform or optical fiber has a glass cooling rate of 4000&#xb0; C./sec or less when attaining a temperature of 1800&#xb0; C.

Method of manufacturing optical fiber

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

The drawing method of the present invention uses a drawing furnace comprising a furnace muffle tube, a furnace body and a heater. According to the method, an optical fiber preform is inserted from the inlet of the furnace muffle tube, the optical fiber preform is melted by means of a heater, under a specified gas atmosphere, and is drawn toward the outlet of the furnace muffle tube by means of a specified drawing tension. The optical fiber preform and the drawing furnace used in this method both satisfy the condition of below-indicated formula (1):&#x2267;8&#x2003;&#x2003;(1)wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform. Through this method, even for the case of drawing optical fibers having a large relative index difference between the central core and the cladding, optical fibers wherein residual amounts of lattice defects are sufficiently reduced and degradation of characteristics under a hydrogen atmosphere is sufficiently suppressed can be obtained efficiently and at low cost.

Drawing method of optical fiber and drawing furnace

An optical fiber comprising a core regiondoped with Cl which raises the refractive index; and a cladding region, provided at the outer periphery of the core region, having a cladding layerdoped with F which lowers the refractive index is formed. The cladding regionto become the outermost cladding layer is configured such that the doping amount of F successively decreases within an outer peripheral partincluding the outer periphery thereof to a predetermined doping amount which is the minimum doping amount of F within the cladding layer. Therefore, the stress within the optical fiber is dispersed into the outer peripheral parthaving an enhanced viscosity, whereby the stress concentration into the core is suppressed. Since the favorable tension range at the time of drawing the optical fiber becomes wider at this time, tension control is facilitated.

Optical fiber, method of making optical fiber preform, and method of making optical fiber

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 furnace for drawing an optical fiber provided with a muffle tube ( ) and inner tubes ( &prime;) connected to the upper end of the core tube, wherein a preform ( ) supported by a dummy rod ( ) at the upper part thereof is disposed inside the muffle tube ( ) and inner tubes ( &prime;) so as to be movable downward together with dummy rod ( ), the preform ( ) is heated and melted by a heater ( ) from the outside of the muffle tube ( ) and an optical fiber ( ) is pulled out from the lower end of the preform ( ); the furnace is further provided with one or a plurality of sets of separating plates ( ) adapted to partition a space in the inner tubes ( &prime;) above the preform ( ) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets ( ) disposed in the parts of wall surfaces of the inner tubes ( &prime;) which are below the separating plates ( ) and adapted to blow an inert gas into the inner tubes ( &prime;) and the muffle tube ( ), thereby preventing variations in diameter of the optical fiber ( ).

Method of controlling an upper portion of an optical fiber draw furnace

A fiber drawing method according to the present invention is a drawing method of optical fiber for drawing an optical fiber from one end of a fiber preform by softening with heat, wherein the fiber preform is set in a semi-closed space opening in part at a lower end in a fiber drawing furnace, the fiber preform is heated by a heater disposed on the lower end side of this semi-closed space and fiber drawing is carried out with adjusting a quantity of heat dissipation from the upper portion of this semi-closed space.

Optical fiber drawing method and drawing furnace

An optical fiber comprising a core region doped with Cl which raises the refractive index; and a cladding region provided at the outer periphery of the core region having a cladding layer doped with F which lowers the refractive index is formed. The cladding region to become the outermost cladding layer is configured such that the doping amount of F successively decreases within an outer peripheral part including the outer periphery thereof to a predetermined doping amount which is the minimum doping amount of F within the cladding layer Therefore, the stress within the optical fiber is dispersed into the outer peripheral part having an enhanced viscosity, whereby the stress concentration into the core is suppressed. Since the favorable tension range at the time of drawing the optical fiber becomes wider at this time, tension control is facilitated.

Optical fiber drawing furnace having adjustable partitions

The present invention provides an optical fiber and the like comprising a structure making it possible to realize optical communications with a higher speed and a larger capacity as compared with conventional optical transmission systems. The optical fiber according to the present invention is an optical fiber in which at least one first portion having a positive chromatic dispersion at a predetermined wavelength within a wavelength band in use and at least one second portion having a negative chromatic dispersion at the predetermined wavelength are arranged adjacent each other along the longitudinal direction thereof. In particular, the optical fiber comprises a polarization coupling structure for inducing coupling between polarization modes of propagating light. This polarization coupling structure randomly causes coupling between polarization modes of the propagating light, whereby polarization mode dispersion decreases at the predetermined wavelength. As a consequence, transmission characteristics are effectively restrained from deteriorating due to polarization mode dispersion. Specifically, the polarization coupling structure is a twist applied to the optical fiber.

Optical fiber, method of making the same, and optical transmission system including the same

Method and apparatus for fabricating coated optical fiber, and coated optical fiber

A manufacturing method of an optical fiber, which enables to precisely manufacture the optical fiber having a desired chromatic dispersion, comprising: (1) preparing an optical fiber preform having a longitudinally uniform refractive index, (2) measuring the chromatic dispersion of a predetermined length of the optical fiber obtained at the beginning of the drawing, (3) according to the results of such measurement, estimating the chromatic dispersion characteristic of the optical fiber obtained by drawing the optical fiber preform, and commencing the drawing of the optical fiber preform. To achieve the target chromatic dispersion diameter of the optical fiber is determined according to the chromatic dispersion that is measured with respect to a predetermined length of an optical fiber obtained at the beginning of the drawing of an optical fiber preform. Then, the remainder of the optical fiber preform is drawn to produce an optical fiber having the desired chromatic dispersion.

Manufacturing method of an optical fiber

A multiple fiber optical cable includes bundled plural optical fibers. In each of the optical fibers to be bundled in the optical cable, a positive dispersion section having a positive chromatic dispersion in an optical signal wavelength and a negative dispersion section having a negative chromatic wavelength and a negative dispersion section having a negative chromatic dispersion section in the optical signal wavelength are alternately arranged so that the chromatic dispersion characteristic of the optical fiber alternately changes in the longitudinal direction. The chromatic dispersion characteristics of the respective bundled plural optical fibers coincide with each other at at least the position of each end of the multiple fiber optical cable. The member which surrounds the optical fibers of the optical cable is provided with the identification marks for identifying the chromatic dispersion characteristics at the individual locations in the longitudinal direction.

Multiple fiber optical cable and method of manufacturing multiple fiber optical cable

The amount of dimming components originating in an ultraviolet-curing resin and adhering to a quartz tube is reduced, and a decline in the ultraviolet transmittance is prevented, during ultraviolet-curing of a resin coated on a liner body through an ultraviolet-transmitting tubular member placed inside a curing apparatus and of curing ultraviolet-curing resin by irradiating ultraviolet rays from outside the ultraviolet-transmitting tubular member. Embodiments include coating the inner surface of the ultraviolet-transmitting tubular member with titanium and employing an atmosphere of lover 0.1% oxygen.

Method and apparatus for curing ultraviolet-curing resin

An optical fiber preform having a viscosity ratio R&eegr;&equals;&eegr; /&eegr; of 2.5 or less between the core average viscosity &eegr; and the total average viscosity &eegr; is prepared, and is drawn by a drawing furnace so as to yield an optical fiber which is then heated to a temperature within a predetermined range so as to be annealed by a heating furnace disposed downstream the drawing furnace Here, upon annealing in the heating furnace the fictive temperature Tf within the optical fiber lowers, thereby reducing the Rayleigh scattering loss. At the same time, the viscosity ratio condition of R&eegr;&lE;2.5 restrains the stress from being concentrated into the core, thereby lowering the occurrence of structural asymmetry loss and the like. Hence, an optical fiber which can reduce the transmission loss caused by the Rayleigh scattering loss and the like as a whole, and a method of making the same can be obtained.

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Yokohama, Japan

Katsuya Nagayama