Abstract: An object of the present invention is to provide a buffered optical fiber, which excels in environmental characteristics and mechanical characteristics and has high flame retardancy and excels in optical transmission characteristics, and to provide a buffered optical fiber, which is terminated with a connector and uses this buffered optical fiber. The buffered optical fiber of the invention is provided with a second coating layer on an outer peripheral surface of an optical fiber produced by providing a first coating layer on an outer peripheral surface of a glass fiber. A second resin composition constituting the second coating layer comprises 100 to 250 weight parts of metal hydroxide and 10 to 100 weight parts of a nitrogen-based flame retardant material per 100 weight parts of the base polymer. Further, the second resin composition does not contain halogenated materials.

Abstract: A plurality of optical fibers are arranged in parallel and peripheries of the plurality of these optical fibers are integrally formed using a sheath. Here, the sheath is formed over the entire length of optical fiber ribbons and a flat portion of the sheath is formed substantially parallel to a common tangent of the neighboring optical fibers. A maximum value of a thickness of the optical fiber ribbons is set to a value which is larger than an outer diameter of the optical fibers by 40 ?m or less. Due to such a constitution, it is possible to easily branch the optical fibers from the integrally formed optical fiber ribbons.

Abstract: In an optical fiber ribbon 1 according to the present invention, four optical fibers 10, 20, 30 and 40 are arranged in parallel to each other in a plane, a part of the periphery of these four optical fibers is covered with a ribbon matrix 51, but no rest thereof is covered with the ribbon matrix. First areas covered with the ribbon matrix 51 and second areas uncovered with the ribbon matrix alternate with each other along the longitudinal direction thereof. Alternatively, the optical fiber ribbon 1 is covered with the ribbon matrix over its entire length. In the glass section of each optical fibers, the mode field diameter defined by the definition of Petermann-I at a wavelength of 1.55 ?m is 8 ?m or less, and the cable cutoff wavelength is 1.26 ?m or less.

Abstract: An object of the present invention is to provide a buffered optical fiber, which excels in environmental characteristics and mechanical characteristics and has high flame retardancy and excels in optical transmission characteristics, and to provide a buffered optical fiber, which is terminated with a connector and uses this buffered optical fiber. The buffered optical fiber of the invention is provided with a second coating layer on an outer peripheral surface of an optical fiber produced by providing a first coating layer on an outer peripheral surface of a glass fiber. A second resin composition constituting the second coating layer comprises 100 to 250 weight parts of metal hydroxide and 10 to 100 weight parts of a nitrogen-based flame retardant material per 100 weight parts of the base polymer. Further, the second resin composition does not contain halogenated materials.

Abstract: In an optical fiber ribbon 1 according to the present invention, four optical fibers 10, 20, 30 and 40 are arranged in parallel to each other in a plane, a part of the periphery of these four optical fibers is covered with a ribbon matrix 51, but no rest thereof is covered with the ribbon matrix. First areas covered with the ribbon matrix 51 and second areas uncovered with the ribbon matrix alternate with each other along the longitudinal direction thereof. Alternatively, the optical fiber ribbon 1 is covered with the ribbon matrix over its entire length. In the glass section of each optical fibers, the mode field diameter defined by the definition of Petermann-I at a wavelength of 1.55 ?m is 8 ?m or less, and the cable cutoff wavelength is 1.26 ?m or less.

Abstract: A plurality of optical fibers are arranged in parallel and peripheries of the plurality of these optical fibers are integrally formed using a sheath. Here, the sheath is formed over the entire length of optical fiber ribbons and a flat portion of the sheath is formed substantially parallel to a common tangent of the neighboring optical fibers. A maximum value of a thickness of the optical fiber ribbons is set to a value which is larger than an outer diameter of the optical fibers by 40 &mgr;m or less. Due to such a constitution, it is possible to easily branch the optical fibers from the integrally formed optical fiber ribbons.

Abstract: In an optical fiber coating method comprising the steps of; applying an injecting first coating resin to the outer periphery of the optical fiber while inserting the optical fiber through a first die hole provided in a first coating die; and applying an injected second coating resin onto the first coating resin while inserting the optical fiber through a second die hole provided in a second coating die.

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: In an optical fiber coating method comprising the steps of; applying an injecting first coating resin to the outer periphery of the optical fiber while inserting the optical fiber through a first die hole provided in a first coating die; and applying an injected second coating resin onto the first coating resin while inserting the optical fiber through a second die hole provided in a second coating die.

Abstract: In a method of making a ribbon type coated optical fiber 3 comprising the step of inserting a plurality of optical fibers 1 flatly arranged parallel to each other through a die orifice 11a so as to collectively coat the optical fibers with a coating resin 2, the ratio W/H of a clearance W in the width direction between the inner surface of the die orifice 11a and the outer surface of the optical fibers 1 to a clearance H in the thickness direction therebetween is set within the range of 1.0 to 2.5.

Abstract: 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.

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: A collectively coating die device (2) is provided for applying coating resin in a lump to coated optical fibers (1) arranged in parallel on one and the same plane so as to form a plurality of optical fiber ribbons (16) at the same time. The collectively coating die device (2) has a nipple portion (9) and a die portion (10), a resin accumulation space (8) formed between the nipple portion (9) and the die portion (10). The nipple portion (9) has two parallel planes and having a plurality of optical fiber passageways (13) shaped like ellipses in section and provided in the direction perpendicular to the planes. The die portion (10) has two parallel planes and has a plurality of optical fiber passageways (14) shaped like ellipses in section and is provided in the direction perpendicular to the planes. Each of the optical fiber passageways (13) of the nipple portion (9) has a tapered portion.

Abstract: An optical fiber making apparatus has a main pipe connected to the furnace core tube, two branch pipes branching from the main pipe, and a gas source, a valve and a flow meter connected to each of the branch pipes. The flows or compositions of the inert gases supplied from the gas sources into the furnace core tube are varied. This changes the amount of heat applied to the lower end of the optical fiber preform, without depending solely on the main heater, to adjust the draw tension and thereby change the local chromatic dispersion along the longitudinal direction of the optical fiber being manufactured.

Abstract: A multiple fiber optical cable includes bundled plural optical fibers which change in chromatic dispersion characteristic in their respective longitudinal directions. 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. Accordingly, the plural optical fibers which change in chromatic dispersion characteristic in their respective longitudinal directions are bundled so that degradations or deviations can be restrained from occurring in the chromatic dispersion characteristics during cutting or connecting or splicing.

Abstract: In a resin coating applicator, a holder 14 is fixed on a base 15 fitted to a drawing machine, and in the holder 14, hot water can be circulated from an inlet 18. The inner circumferential surface of the holder 14 is formed into a tapered shape so that the outer circumferential surface of a cup-like member 4 of a cartridge type coating sub-assembly 1 is fitted to the holder 14. The respective outer circumferential surfaces of a nipple 2 and a coating die 3 are cylindrical so as to be fitted to the inner circumferential surfaces of an inner cylindrical member 6, and they are positioned by a step portion. Further, they are pressed from the upper and lower sides by the bottom portion of the cup-like member 4 and a lid member 5. The lid member 5 is fastened to the cup-like member 4 integrally by a thread.

Abstract: In a split type ribbon optical fiber core cable capable of being split into cables, there are a plurality of ribbon optical fiber core cable units, each of which are constituted by a plurality of colored optical fiber core cables arranged in a row; a coating resin of an ultraviolet curable resin wholly coats the plurality of colored optical fiber core cables; and a bonding resin of an ultraviolet curable resin bonds the ribbon optical fiber core cable units arranged in a row. In this cable, an adhesion strength between the coating resin and the bonding resin is in the range of 1 to 100 g/cm. Further, the bonding resin after curing has a Young's modulus of from 5 to 100 kg/mm.sup.2. The bonding resin after curing has an elongation coefficient of from 5 to 80%.

Abstract: The present invention relates to an optical fiber coating method and an apparatus therefor which can form high quality coating layer on an optical fiber (12) by preventing non-concentricity of a coating resin (14) applied on the optical fiber (12) and admixing of bubble.

Abstract: An optical fiber ribbon is manufactured under a condition where, assuming that the optical fiber ribbon has a thickness of 2d (mm), a guide roller has a diameter of 2R (mm), and a period of time till the optical fiber ribbon comes into contact with the guide roller after leaving an ultraviolet irradiation apparatus is t (ms), a relationship of d/?(R+d).times.t!<0.2 is satisfied. Accordingly, no damages are imparted to the optical fiber ribbon, and no micro-bendings occur in its coated optical fibers, whereby the transmission characteristic can be prevented from deteriorating.

Abstract: In a method for producing an optical fiber ribbon, a plurality of coated optical fibers is fed out so that the plurality of coated optical fibers are arranged in a plane in a concentrator. A ribbon matrix composed of ultraviolet-curing resin is applied onto the plurality of coated optical fibers in a coater. Ultraviolet rays is radiated to cure the ribbon matrix. The plurality of coated optical fibers are arranged at intervals in a plane in the concentrator.