Sumitomo Electric Industries, Limited

Eiji Yanada

Masaaki Hirano

Masashi Onishi

Yuichi Ohga

Eisuke Sasaoka

Tomoyuki Yokokawa

Masao Tsukitani

Atsushi Inoue

Kazuyuki Sohma

Tadashi Enomoto

Hideyuki Ijiri

Tomomi Moriya

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

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&#x2267;Nr&#x3e;No&#x3e;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.

Optical fiber preform producing method, optical fiber production method, and optical fiber

A method for manufacturing an optical fiber preform that can produce an optical fiber having desired characteristics over the longer length thereof. A crude preform provided with a core region and a cladding region is prepared (Step S), and at a plurality of positions in the longitudinal direction of the crude preform, a refractive index profile in the cross-section of the crude preform is measured (Step S). Then, the shape of the cladding region is demarcated based on the shape of the profile (Step S). Subsequently, the crude preform is ground based on the results of the demarcation (Step S). Thus, an optical fiber preform that enables the manufacture of an optical fiber having target characteristics is manufactured.

Manufacturing method of optical fiber preform

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 fiberincluding forming a glass pipeby applying a ring portionon the inner face of a starting pipeas a starting material, inserting a glass rodthat becomes a central core portionand a depressed portioninto the inside of the glass pipe, integrating the glass pipeand the glass rodby collapse to form a glass body, forming a preformby providing a jacket portionoutside the glass body, and drawing the preform, wherein the thickness of the starting pipeis set in a range from 4 mm to 8 mm.

Optical fiber manufacturing method and optical fiber

Stress exerted on an inner or outer circumferential side of a glass tubeis controlled when a glass materialis heated and softened by a heating elementprovided around the glass materialand a piercing plugis relatively pressed into a softened region of the glass materialto thereby form the glass materialinto the glass tubegradually. For example, the control of the stress can be carried out by controlling an internal or external pressure of the glass tube. As a result, the deformation of the glass tubejust after piercing is prevented so that the glass tubecan be obtained with high quality. It is also possible to solve the problem that cracks may occur easily at the time of reheating because of residual stress distribution after cooling.

Method and apparatus for manufacturing glass tube

There is disclosed a dispersion-compensating optical fiber exhibiting, at a wavelength of 1500 nm, a chromatic dispersion of &#x2212;30 ps/nm/km or less, a ratio (S/D) of &#x2212;0.08/nm to +0.05/nm between chromatic dispersion D and dispersion slope S, a polarization mode dispersion of 0.3 ps/kmor less, and a transmission loss of 1 dB/km or less, and an excess loss of 0.2 dB/km or less due to OH group in a wavelength band of 1.4 &#x3bc;m.

Dispersion-compensating optical fiber and optical transmission line

An optical fiber preform having a low core noncircularity and eccentricity for producing an optical fiber having an improved polarization mode dispersion, a method for producing the preform, and an optical fiber produced from the preform. The optical fiber preform is produced by the following steps. Diameter-reduced portions and are formed in the vicinity of the ends of the glass pipe . A glass rod is inserted into the glass pipe . The glass rod is fixed to the glass pipe at the diameter-reduced portion . The glass pipe and the glass rod are heat-unified from the diameter-reduced portion forward to the diameter-reduced portion . The optical fiber preform has a core noncircularity of at most 1.5%. The optical fiber has a polarization mode dispersion of at most 0.15 ps/km at a wavelength of 1,550 nm.

Optical fiber preform, production method thereof, and optical fiber produced from the preform

The present invention relates to an optical transmission line suitably used for a large-capacity high-speed WDM optical transmission system, and an optical fiber suitably used for such an optical transmission line. The optical transmission line is formed by connecting a single-mode optical fiber (SMF) and a dispersion compensating optical fiber (DCF). The dispersion compensating optical fiber has a dispersion value D (unit: ps/nm/km) and dispersion slope S (unit: ps/nm /km) falling within the ranges of &minus;82 &lE;D &lE;&minus;29 and 0.0023&times;D &lE;S &lE;0.033&plus;0.0015&times;D at a wavelength of 1,550 nm, respectively. At the wavelength of 1,550 nm, the transmission loss is 0.5 dB/km or less. Letting L be the length of the dispersion compensating optical fiber, and L be the length of the single-mode optical fiber, the value L /(L &plus;L ) in the optical transmission line is 0.2 to 0.4. This optical transmission line can suppress the nonlinear optical phenomenon and is suitable to long-distance large-capacity transmission because the optical transmission line has a small transmission loss and low nonlinear index.

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Yokohama, Japan

Eiji Yanada