Abstract: The present invention relates to a compact dispersion compensator and the like. The dispersion compensator comprises a housing and an optical fiber coil. The optical fiber coil has a coiled part constituted by a dispersion-compensating optical fiber wound like a coil while being in a bundle state with its winding distortion substantially eliminated. The housing is filled with a resin surrounding the coiled part of the optical fiber coil, whereas the coiled part is held by the resin. By this structure, the dispersion compensator can realize a further compactness.

Abstract: An optical cable according to the present invention relates to an optical cable having a construction to enable reduction of a cable outer diameter, and/or improvement of contained efficiency of coated optical fibers while an increase of transmission loss in each coated optical fiber is suppressed. The optical cable has a loose-tube type of structure constructed by: a tension member; a plurality of tubes stranded together around the tension member; and an outer sheath covering the outer periphery of the plurality of tubes. One or more coated optical fibers are contained in each tube. A ratio of A/B is 6.3 or more but 7.0 or less, where each coated optical fiber has a mode field diameter A in a range of 8.6±0.4 ?m at a wavelength of 1.31 ?m, and where a fiber cutoff wavelength thereof is B ?m.

Abstract: The present invention relates to a compact dispersion compensator and the like. The dispersion compensator comprises a housing and an optical fiber coil. The optical fiber coil has a coiled part constituted by a dispersion-compensating optical fiber wound like a coil while being in a bundle state with its winding distortion substantially eliminated. The housing is filled with a resin surrounding the coiled part of the optical fiber coil, whereas the coiled part is held by the resin. The dispersion-compensating optical fiber constituting the optical fiber coil has a chromatic dispersion of ?140 ps/nm/km or less at a wavelength of 1.55 ?m, whereas the housing has a volume of 500 cm3 or less. This configuration allows the dispersion compensator to attain an accumulated chromatic dispersion of ?1200 ps/nm/km or more but less than ?600 ps/nm at a wavelength of 1.55 ?m.

Abstract: Methods of manufacturing an optical fiber preform and an optical fiber, and an optical fiber formed by this method of manufacturing an optical fiber are provided, the optical fiber preform having a desired refractive index profile and being capable of suppressing an increase in loss due to the absorption by OH groups. A pipe is formed by an inside vapor phase deposition method such that glass layer to be formed into a core and a glass layer to be formed into a part of a cladding pipe are deposited in a starting pipe, the glass layers each containing at least one of fluorine, germanium, phosphorous, and chlorine, the starting pipe being made of a silica glass having an outside diameter in the range of 20 to 150 mm and a wall thickness in the range of 2 to 8 mm. The pipe thus formed is collapsed to form a glass rod in which the concentration of hydroxyl groups is 10 weight ppm or less in a region from the surface of the glass rod to a depth of 1 mm therefrom.

Abstract: An optical fiber preform comprises a central core portion having a maximal value Nc of refractive index in the center, and outside the central core portion, comprising at least a depressed portion having a minimal value Nd of refractive index, a ring portion having a maximal value Nr of refractive index and an outside cladding layer having a maximal value No of refractive index. The optical fiber preform satisfies a relation of Nc?Nr>No>Nd among the values of refractive index. A method of the optical fiber preform comprises fabricating a glass rod by inserting a rod containing at least the central core portion into a pipe containing at least the depressed portion and integrating them, fabricating a glass pipe having the ring portion, and fabricating a vitreous body by integrating the glass rod and the glass pipe by collapsing after inserting the glass rod into the glass pipe.

Abstract: The present invention relates to a dispersion compensation unit capable of compensating for both the chromatic dispersion and dispersion slope of a non-zero dispersion-shifted optical fiber. The dispersion compensation unit is formed by winding a first optical fiber and second optical fiber into coil shapes and storing them in a case. The first optical fiber has a negative chromatic dispersion D1 and a negative dispersion slope S1 at a wave length in use. The second optical fiber has a positive chromatic dispersion D2 and a positive dispersion slope S2 at the wavelength in use.

Abstract: An object of the present invention is to provide an optical fiber manufacturing method and an optical fiber in which an increase in the transmission loss is suppressed by preventing hydroxyl group from entering near the core portion. This invention provides a method for manufacturing an optical fiber 10 including forming a glass pipe 16 by applying a ring portion 15 on the inner face of a starting pipe 14 as a starting material, inserting a glass rod 13 that becomes a central core portion 11 and a depressed portion 12 into the inside of the glass pipe 16, integrating the glass pipe 16 and the glass rod 13 by collapse to form a glass body 17, forming a preform 10a by providing a jacket portion 18 outside the glass body 17, and drawing the preform 10a, wherein the thickness of the starting pipe 14 is set in a range from 4 mm to 8 mm.

Abstract: In a glass processing method according to the invention, in the case of performing chemical vapor deposition or diameter shrinkage of a substrate glass tube G by relatively moving a heating furnace 20 comprising a heating element 21 for annularly enclosing the circumference of the substrate glass tube in a longitudinal direction of the substrate glass tube G with respect to the substrate glass tube G in which an outer diameter is 30 mm or more and a wall thickness is 3 mm or more and is less than 15 mm and an ovality of the outer diameter is 1.0% or less using a glass processing apparatus 1, a temperature of at least one of the heating element 21 and the substrate glass tube G is measured and the amount of heat generation of the heating element 21 is adjusted based on the measured temperature.

Abstract: To provide a manufacturing method for an optical fiber preform and a manufacturing method for an optical fiber in which the optical fiber with a complex profile is produced at high precision, and an optical fiber.

Abstract: An object of the present invention is to provide an optical fiber manufacturing method and an optical fiber in which an increase in the transmission loss is suppressed by preventing hydroxyl group from entering near the core portion.

Abstract: An optical fiber cable produced at low cost is provided, in which an optical fiber core covered with an outer covering is suppressed from moving inside the outer covering in the lengthwise direction thereof and which does not cause the transmission characteristics to be deteriorated even when the cable is bent. In the optical fiber cable, buffer members composed of a long fiber are longitudinally disposed or stranded around at least one optical fiber core, the buffer members and the optical fiber core are adhered together intermittently in the lengthwise direction, and an outer covering is provided to surround the buffer members.

Abstract: The present invention relates to a compact dispersion compensator and the like. The dispersion compensator comprises a housing and an optical fiber coil. The optical fiber coil has a coiled part constituted by a dispersion-compensating optical fiber wound like a coil while being in a bundle state with its winding distortion substantially eliminated. The housing is filled with a resin surrounding the coiled part of the optical fiber coil, whereas the coiled part is held by the resin. By this structure, the dispersion compensator can realize a further compactness.

Abstract: The present invention relates to a compact dispersion compensator and the like. The dispersion compensator comprises a housing and an optical fiber coil. The optical fiber coil has a coiled part constituted by a dispersion-compensating optical fiber wound like a coil while being in a bundle state with its winding distortion substantially eliminated. The housing is filled with a resin surrounding the coiled part of the optical fiber coil,whereas the coiled part is held by the resin. The dispersion-compensating optical fiber constituting the optical fiber coil has a chromatic dispersion of −140 ps/nm/km or less at a wavelength of 1.55 &mgr;m, whereas the housing has a volume of 500 cm3 or less. This configuration allows the dispersion compensator to attain an accumulated chromatic dispersion of −1200 ps/nm/km or more but less than −600 ps/nm at a wavelength of 1.55 &mgr;m.

Abstract: The present invention relates to a dispersion compensation unit capable of compensating for both the chromatic dispersion and dispersion slope of a non-zero dispersion-shifted optical fiber. The dispersion compensation unit is formed by winding a first optical fiber and second optical fiber into coil shapes and storing them in a case. The first optical fiber has a negative chromatic dispersion D1 and a negative dispersion slope S1 at a wave length in use. The second optical fiber has a positive chromatic dispersion D2 and a positive dispersion slope S2 at the wavelength in use.

Abstract: A cable and a cable stripping method which facilities the stripping of an intermediate part of a cable having a cable core covered by a plastic sheath provided around the outer periphery without damaging the cable core. In a cable having a plastic sheath 2 on a cable core 1, either a groove 2a is provided in the inner surface of the plastic sheath 2 extending in the longitudinal direction of the cable. A ripcord 3 is either fitted in the groove 2a or adhered to the inner surface of the plastic sheath. In either case, the position-indicating means 2b showing the position of the ripcord is provided on the outer surface of the plastic sheath 2 at the point where the ripcord 3 is fitted.

Abstract: The invention is to provide an optical fiber cable in which an end of an optical fiber core is prevented from being dragged inside the main cable body part upon the application of a tension on the optical fiber cable, and which prevents the increase in transmission loss and breakage of the optical fiber core caused by the movement of the optical fiber core near the connection point. The invention can be characterized in that an optical fiber cable is formed in such a manner that yarns are stranded in a periphery of the stack of the optical fiber ribbons, and an outer sheath of the main cable body part is formed with a tension member united thereto on the periphery of the yarns.

Abstract: A cable and a cable stripping method which facilitates the stripping of an intermediate part of a cable comprising a cable core covered by a plastic sheath provided around the outer periphery without damaging the cable core. In a cable having a plastic sheath 2 on a cable core 1, either a groove 2a is provided in the inner surface of the plastic sheath 2 extending in the longitudinal direction of the cable and a ripcord 3 is fitted in the groove 2a or a ripcord 3 is adhered to the inner surface of the plastic sheath, and in either case the position-indicating means 2b showing the position of the ripcord is provided on the outer surface of the plastic sheath 2 at the point where the ripcord 3 is fitted.

Abstract: An optical fiber cable in which optical fiber ribbon stack can be accommodated in a cylindrical space efficiently and which has excellent loss characteristic. A plurality of optical fiber ribbons 1 are stacked. Cushioning fillers 2 are disposed around the optical fiber ribbon stack 1. The optical fiber ribbon stack 1 and the cushioning fillers 2 are accommodated in a cylindrical member 3. The space factor of the cushioning fillers in the inner space of the cylindrical member as a remainder after removal of the optical fiber ribbon stack from the inner space is from 10 to 60%. Consequently, the optical fiber cable becomes excellent both in initial transmission loss and in loss increasing characteristic at a low temperature.

Abstract: A spacer having a high-tensile member at the center thereof has grooves extending helically. Coated optical fibers have been disposed in each groove. This assembly is covered with a wound covering and further with a sheath. The proportion of the total sectional area of the coated optical fibers to the sectional area of each groove, i.e., the degree of packing, is regulated to 10 to 50%.