Abstract: A drawing apparatus 1 comprises a drawing furnace 11, a protecting tube 21, and a resin curing unit 31. A buffer chamber 41 is disposed between the drawing furnace 11 and the protecting tube 21, and has a length L1 in the drawing direction of the optical fiber 3. The buffer chamber 41 is constituted by a first buffer cell 42 and a second buffer cell 45. In the space within the buffer chamber 41, an He gas, which is an atmosphere gas within the drawing furnace 11, and the air, which is an atmosphere gas within the protecting tube 21, exist in a mixed state. The optical fiber 3 drawn upon heating in the drawing furnace 11 is fed to the protecting tube 21, and a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. Thereafter, a coating die 62 coats the optical fiber 3 with a UV resin solution 63, and the resin curing unit 31 cures the UV resin 63, whereby a coated optical fiber 4 is obtained.

Abstract: 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): L/D?8??(1) wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform.

Abstract: A method produces an optical fiber without requiring a vertically large space, and an apparatus implements the method. The method produces an optical fiber by heating a lower-end portion of an optical fiber preform with a heating element so that the optical fiber preform can be drawn. In this method, the optical fiber preform is drawn by moving a heat-generating portion of the heating element from the lower-end portion toward an upper-end portion of the optical fiber preform. The apparatus produces an optical fiber by heating a lower-end portion of an optical fiber preform with a heating element so that the optical fiber preform can be drawn. The apparatus comprises a mechanism for moving a heat-generating portion of the heating element from the lower-end portion toward an upper-end portion of the optical fiber preform.

Abstract: The present invention relates to an optical fiber comprising a structure enabling WDM transmissions by utilizing the whole wavelength range of 1300 nm to 1625 nm as a signal wavelength band. In the optical fiber according to the present invention, the transmission loss is 0.4 dB/km or less at a wavelength of 1310 nm, 0.4 dB/km or less at a wavelength of 1383 nm, and 0.3 dB/km or less at a wavelength of 1550 nm. The chromatic dispersion is 0.1 ps/nm/km or more but 5.5 ps/nm/km or less at a wavelength of 1383 nm, and 0.1 ps/nm/km or more but 16.5 ps/nm/km or less in the wavelength range of 1530 nm to 1565 nm. The cut off wavelength at a length of 22 m is 1300 nm or less, and the absolute value of dispersion slope in the wavelength range of 1300 nm to 1625 nm is 0.1 ps/nm2/km or less.

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5,5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5,5′) which are below the separating plates (4, 17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muff

Abstract: A fiber drawing method according to the present invention is a drawing method of optical fiber for drawing an optical fiber 14 from one end of a fiber preform 13 by softening with heat, wherein the fiber preform 13 is set in a semi-closed space 10, 20 opening in part at a lower end in a fiber drawing furnace, the fiber preform 13 is heated by a heater 15 disposed on the lower end side of this semi-closed space 10, 20, and fiber drawing is carried out with adjusting a quantity of heat dissipation from the upper portion 20 of this semi-closed space.

Abstract: A method capable of stably drawing an optical fiber with a gas-seal system and an apparatus for implementing the method. The method produces an optical fiber 40b by drawing the optical fiber preform 30 by heating and softening the leading-end portion of it while feeding it into a drawing furnace 20. The drawing furnace 20 allows a gas 15 to blow against the optical fiber preform 30. The inside of the drawing furnace 20 is sealed with a seal ring 14U and a shutter 14L located at the top and bottom portions of it, respectively. While the gas 15 is fed, the inner diameter of the seal ring 14U is adjusted according to the diameter of the optical fiber preform 30. Consequently, even when the preform diameter varies, the clearance between the seal ring 14U and the optical fiber preform 30 can be maintained constant, thereby enabling a stable drawing operation.

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5, 5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5, 5′) which are below the separating plates (4,17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muf

Abstract: A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5, 5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5, 5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5, 5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5, 5′) which are below the separating plates (4, 17) and adapted to blow an inert gas into the inner tubes (5, 5′) and the

Abstract: 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.

Abstract: There is provided an optical fiber drawing furnace capable of drawing an optical fiber having small non circularity, which drawing furnace includes a muffle tube, in which an optical fiber preform is supplied, a heater surrounding the muffle tube, a plurality of electrode connecting portion extending from the heater, a plurality of electrodes connected to electrode connecting portions, and in conjunction therewith to an electric power source, and unifying means for unifying the temperature distribution along the circumferential direction.

Abstract: A method of drawing an optical fiber which can improve the efficiency in manufacture without deforming resin coatings is provided.

Abstract: A method of making an optical fiber employing a wavelength in an infrared region as a wavelength band in use is provided, in which an optical fiber 1 is exposed to an atmosphere containing hydrogen at a concentration of 0.05 vol % but not higher than 4.0 vol % after being drawn and taken up with a bobbin 2 before being put into use, whereas the hydrogen treatment temperature is lower than 50° C., preferably 30° C. or lower, more preferably at room temperature, whereby the increase in loss caused by hydrogen is small even when the optical fiber is used in a wide band, so that the optical fiber can be made efficiently and safely with an optimal hydrogen treatment.

Abstract: 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.

Abstract: 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° C., whereas the optical fiber preform or optical fiber has a glass cooling rate of 4000° C./sec or less when attaining a temperature of 1800° C.

Abstract: 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.

Abstract: 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.

Abstract: The present invention relates to an optical fiber comprising a structure enabling WDM transmissions by utilizing the whole wavelength range of 1300 nm to 1625 nm as a signal wavelength band. In the optical fiber according to the present invention, the transmission loss is 0.4 dB/km or less at a wavelength of 1310 nm, 0.4 dB/km or less at a wavelength of 1383 nm, and 0.3 dB/km or less at a wavelength of 1550 nm. The chromatic dispersion is 0.1 ps/nm/km or more but 5.5 ps/nm/km or less at a wavelength of 1383 nm, and 0.1 ps/nm/km or more but 16.5 ps/nm/km or less in the wavelength range of 1530 nm to 1565 nm. The cut off wavelength at a length of 22 m is 1300 nm or less, and the absolute value of dispersion slope in the wavelength range of 1300 nm to 1625 nm is 0.1 ps/nm2/km or less.

Abstract: 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.

Abstract: When drawing an optical fiber from a preform, positive and negative dispersion sections of an optical fiber are provided, respectively, with target glass diameters different from each other, whereby the positive and negative dispersion sections attain their respective desirable values of chromatic dispersion. Also, the positive and negative dispersion sections and a transient section therebetween are provided, respectively, with values of control constant different from each other, which are used to converge the measured glass diameter to said target diameter, for adjusting the drawing speed, whereby the transient section is shortened. Alternatively, the positive and negative dispersion sections of the optical fiber are provided with respective target drawing speeds different from each other, whereby the transient section is shortened.