Sumitomo Electric Industries, Limited

Yuji Kubo

Makoto Shimizu

Masashi Onishi

Takatoshi Kato

Toshiyuki Miyamoto

Shigeru Tanaka

Tomoyuki Hattori

Yoshiaki Terasawa

Kazuya Kuwahara

Katsuyuki Tsuneishi

Koji Shimoda

An optical fibercomprising a glass portionhaving a coreand a cladding, and one or more covering layersformed around the glass portion, in which an arrangement form of the covering layerwith respect to the glass portionin cross section perpendicular to a longitudinal direction thereof is changed continuously in the longitudinal direction thereof.

Optical fiber and method of manufacturing the optical fiber

An optical fiber and an optical transmission system are provided which enable a large-volume and long-haul transmission, using light signals having a plurality of wavelengths in a wide range of wavelength bands including 1.31 &#x3bc;m band, 1.45 &#x3bc;m band, 1.55 &#x3bc;m band and 1.58 &#x3bc;m band. The chromatic dispersion of the optical fiber according to the present invention is &#x2212;20 ps&#x2022;nm&#x2022;kmor more but &#x2212;3 ps&#x2022;nm&#x2022;kmor less in the whole wavelength range of 1300 nm to 1600 nm. The optical transmission system according to the present invention is also equipped with (1) a plurality of transmitters to transmit light signals having wavelengths in the range of 1300 nm to 1600 nm, (2) an optical fiber of the present invention, and (3) receivers which receive the light signals.

Optical fiber and optical transmission system

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/nm/km or less.

Optical fiber

The present invention relates to an optical fiber transmission line and the like comprising a structure for enabling repeating sections to become further longer. The optical fiber transmission line comprises first and second optical fibers successively disposed along the traveling direction of signal light, and an optical multiplexer for supplying Raman amplification pumping light to one of the first and second optical fibers. The first and second optical fibers are optically connected to each other. The second optical fiber has an effective area smaller than that of the first optical fiber, and a chromatic dispersion and a length which are different from those of the first optical fiber. In particular, the respective lengths of the first and second optical fibers are appropriately regulated so as to effectively suppress nonlinear phenomena other than Raman amplification.

Optical fiber transmission line, optical cable, and optical transmission system

The optical transmission system in accordance with the present invention is an optical transmission system in which an optical fiber transmission line is laid between a transmitting station and a receiving station, first and second optical couplers are provided on the optical fiber transmission line, a first Raman amplification pumping light source is connected to the first optical coupler, a second Raman amplification pumping light source is connected to the second optical coupler, the optical fiber transmission line Raman-amplifies signal light in S band when Raman amplification pumping light is supplied thereto while transmitting the signal light, and the optical fiber transmission line has a zero-dispersion wavelength of 1350 nm to 1440 nm and a cable cutoff wavelength of less than 1368 nm.

Optical transmission system

The heat-resistant coated optical fiber in accordance with the present invention comprises a coating portion , coated on the outer periphery of an optical fiber , comprising a first coating layer consisting of aromatic polyimide resin, a second coating layer consisting of silicone resin, and a third coating layer consisting of moisture-resistant resin with a heat resistance equivalent to that of the first coating layer , e.g., PFA.

Heat resistant optical fiber core

The present invention relates to an optical fiber transmission line and the like comprising a structure for enabling repeating sections to become further longer. The optical fiber transmission line comprises first and second optical fibers successively disposed along the advancing direction of signal light, and an optical multiplexer for supplying Raman amplification pumping light to one of the first and second optical fibers. The first and second optical fibers are fusion-spliced to each other, whereas at least one of them has a core region substantially made of pure silica glass. The second optical fiber has an effective area smaller than that of the first optical fiber, and a chromatic dispersion and a length which are different from those of the first optical fiber. In particular, the respective lengths of the first and second optical fibers are appropriately regulated so as to effectively suppress nonlinear phenomena other than Raman amplification.

An optical fiber that can sufficiently suppress the generation of four-wave mixing and that can widen the bandwidth of wavelength of signal light. The optical fiber of the present invention has (a) a chromatic dispersion whose absolute value is not less than 8 ps&middot;nm &middot;km and not more than 15 ps&middot;nm &middot;km at a wavelength of 1.55 &mgr;m and (b) a dispersion slope whose absolute value is not more than 0.05 ps&middot;nm &middot;km at a wavelength of 1.55 &mgr;m. It is more desirable that the optical fiber have (a) a chromatic dispersion whose absolute value is not less than 8 ps&middot;nm &middot;km and not more than 12 ps&middot;nm &middot;km at a wavelength of 1.55 &mgr;m, (b) a dispersion slope whose absolute value is not more than 0.03 ps&middot;nm &middot;km at a wavelength of 1.55 &mgr;m, (c) a chromatic dispersion whose absolute value is not less than 5 ps&middot;nm &middot;km at wavelengths between 1.45 and 1.65 &mgr;m, (d) an effective area not less than 45 &mgr;m at a wavelength of 1.55 &mgr;m, and (e) a two-meter cutoff wavelength not less than 1.40 &mgr;m.

Optical fiber suitable for use in WDM transmission system

An optical fiber whose chromatic dispersions have an opposite sign relative to those of the 1380 nm zero-dispersion fiber at all of the wavelengths in the range of 1450 nm to 1620 nm is provided. This optical fiber has negative chromatic dispersions at all of the wavelengths in this range and the values of which are &minus;7 ps&middot;nm &middot;km or more but &minus;1 ps&middot;nm &middot;km or less at a wavelength of 1450 nm, &minus;12 ps&middot;nm &middot;km or more but &minus;5 ps&middot;nm &middot;km or less at a wavelength of 1550 nm and &minus;17 ps&middot;nm &middot;km or more but &minus;6 ps&middot;nm &middot;km or less at a wavelength of 1620 nm. This optical fiber can compensate the dispersions of 1380 nm zero-dispersion fiber over the entire wavelength in this range.

A single mode optical fiber of the present invention includes an inner core portion having a diameter of 2a and a refractive index n.sub.1, an outer core portion having a diameter of 2b and a refractive index n.sub.2 which is smaller than the refractive index n.sub.1 of the inner core portion, the outer core being disposed around the inner core, a clad portion disposed around the outer core portion having a refractive index n.sub.0. The single mode optical fiber satisfies relations of: 0.70%.ltoreq..DELTA.n.sub.1 .ltoreq.1.2%, 0.12.ltoreq..DELTA.n.sub.2 /.DELTA.n.sub.1 .ltoreq.0.16, and 0.15.ltoreq.2a/2b.ltoreq.0.25; 0.70%.ltoreq..DELTA.n.sub.1 .ltoreq.0.85%, 0.06.ltoreq..DELTA.n.sub.2 /.DELTA.n.sub.1 .ltoreq.0.12, and 0.20.ltoreq.2a/2b.ltoreq.0.28; or .DELTA.n.sub.1 .ltoreq.0.7%, 0.06.ltoreq..DELTA.n.sub.2 /.DELTA.n.sub.1 .ltoreq.0.16, and 0.15.ltoreq.2a/2b.ltoreq.0.3; where .DELTA.n.sub.1 =(n.sub.1.sup.2 -n.sub.0.sup.2)/n.sub.1.sup.2, and .DELTA.n.sub.2 =(n.sub.2.sup.2 -n.sub.0.sup.2)/n.sub.2.sup.2.

Growing community of inventors

Yokohama, Japan

Yuji Kubo