Fujikura Limited

Takaaki Suzuki

Kazuhiko Aikawa

Kuniharu Himeno

Shoichiro Matsuo

Shogo Shimizu

Ryozo Yamauchi

Akira Wada

Manabu Saitou

Masakazu Nakayama

Takashi Suzuki

Koichi Harada

Keiji Ohashi

Munehisa Fujimaki

Yutaka Nagasawa

Ryuji Suzuki

A dispersion shifted optical fiber where a radius rof a first center segment is 0.5 &#x3bc;m to 2.8 &#x3bc;m, and a relative refractive index difference &#x394;is 0.4% or more and 0.9% or less. A radius rof a first segment is 1.8 &#x3bc;m or more and 4.5 &#x3bc;m or less. A radius rof a second segment is 4.0 &#x3bc;m or more and 8.0 &#x3bc;m or less, and a relative refractive index difference &#x394;is 0.00% or more and 0.07% or less. A radius rof a third segment is 4.5 &#x3bc;m or more and 8.5 &#x3bc;m or less, and a relative refractive index difference &#x394;is 0.285% or more and 0.5% or less. A radius rof a fourth segment is 8.0 &#x3bc;m or more and 16.0 &#x3bc;m or less, and a relative refractive index difference &#x394;is 0.005% or more and 0.04% or less.

Dispersion shifted optical fiber

A dispersion compensating optical fiber for NZ-DSFs, includes: an uncovered dispersion compensating optical fiber; a double-layered resin coating disposed around the uncovered dispersion compensating optical fiber; and an outer coating layer having a thickness of 3 to 7 &#x3bc;m, containing silicone in an amount of 1 to 5% by weight, and disposed around the double-layered resin coating. The outer diameter of the uncovered dispersion compensating optical fiber is in a range from 90 to 125 &#x3bc;m, an outer diameter of the dispersion compensating optical fiber is in a range from 180 to 250 &#x3bc;m, and the amount of silicone contained in the outer coating layer is determined such that an adhesive property of the outer coating layer is 1 gf/mm or less.

Dispersion compensating optical fiber and dispersion compensating optical fiber module

An optical fiber is fabricated with a refractive index profile having a central core; a middle part provided around the outer periphery of the central core and having a lower refractive index than that of the central core; and a cladding provided around the periphery of the middle part and having a higher refractive index than the middle part and a lower refractive index than the central core. This optical fiber has an effective core area of 120 &#x3bc;mor more in an employed wavelength band selected from the range of 1.53&#x2dc;1.63 &#x3bc;m, and has a cut-off wavelength that is capable of substantially single mode propagation in the aforementioned employed wavelength band. As a result, it is possible to construct an optical transmission system having excellent transmission characteristics in which nonlinearity is decreased.

Optical fiber and optical transmission system

In fusion-splicing a dispersion compensating optical fiber having a negative dispersion slope, with a connection optical fiber having a different near field pattern from that of the dispersion compensating optical fiber, if for the connection optical fiber, one is selected such that a theoretical joint loss in a used wavelength, obtained from an overlap integral of a near field pattern of the dispersion compensating optical fiber after fusion splicing and a near field pattern of the connection optical fiber after fusion splicing is presumed to be 0.3 dB or less, in an unconnected state, a construction enabling connection at a low loss results.

Joint loss minimizing connection structure for dispersion compensating optical fiber

In order to provide a dispersion-compensating optical fiber able to be applied over a broad wavelength band, having a large effective area, and as a result, suppressing the occurrence of non-linear effects, the present invention comprises a dispersion-compensating optical fiber that compensates chromatic dispersion of a 1.3 &#x3bc;m single-mode optical fiber over the entire wavelength range of 1.53-1.63 &#x3bc;m characterized in that, chromatic dispersion at a wavelength of 1.55 &#x3bc;m is &#x2212;50 ps/nm/km or less, the dispersion slope is negative over the entire wavelength range of 1.53-1.63 &#x3bc;m, a cutoff wavelength is provided at which there is substantially single-mode propagation, bending loss is 30 dB/m or less, effective area is 20 &#x3bc;mor more, and the absolute value of chromatic dispersion during compensation of the chromatic dispersion of a 1.3 &#x3bc;m single-mode optical fiber serving as the target of compensation is 0.5 ps/nm/km or less.

Dispersion-compensating optical fiber and hybrid transmission line

A dispersion compensating optical fiber includes an uncovered dispersion compensating optical fiber containing a core and a cladding, and a resin coating which is disposed around the uncovered dispersion compensating optical fiber, wherein the resin coating has an adhesive property of 10 g/mm or less, and which includes an outer coating layer which is formed to have a thickness of 3 &#x3bc;m or more, and the outer diameter of the uncovered dispersion compensating optical fiber is in a range from 90 to 125 &#x3bc;m, and the outer diameter of the dispersion compensating optical fiber is in a range from 180 to 250 &#x3bc;m.

A dispersion compensating fiber, which has a negative dispersion slope with a large absolute value while maintaining the absolute value of the chromatic dispersion, and which has sufficient dispersion slope compensation properties even for the non-zero dispersion shifted optical fiber requiring a large RDS for dispersion compensation. In this dispersion compensating fiber, the radius of a ring core region is set in a range from 6.7 &#x3bc;m to 10.7 &#x3bc;m, the radius ratio of a depressed core region relative to a central core region is set in a range from 2.0 to 3.0, and the radius ratio of the ring core region relative to the depressed core region is set in a range from 1.3 to 2.0, the relative refractive index difference of the central core region relative to the cladding is set in a range from +1.00% to +1.80%, the relative refractive index difference of the depressed core region relative to the cladding is set in a range from &#x2212;1.20% to &#x2212;1.50%, and the relative refractive index difference of the ring core region relative to the cladding is set in a range from +0.20% to +0.50%.

Dispersion compensating fiber and dispersion compensating fiber module

In order to provide a dispersion-compensating optical fiber able to be applied over a broad wavelength band, having a large effective area, and as a result, suppressing the occurrence of non-linear effects, the present invention comprises a dispersion-compensating optical fiber that compensates chromatic dispersion of a 1.3 &mgr;m single-mode optical fiber over the entire wavelength range of 1.53-1.63 &mgr;m characterized in that, chromatic dispersion at a wavelength of 1.55 &mgr;m is &minus;50 ps/nm/km or less, the dispersion slope is negative over the entire wavelength range of 1.53-1.63 &mgr;m, a cutoff wavelength is provided at which there is substantially single-mode propagation, bending loss is 30 dB/m or less, effective area is 20 &mgr;m or more, and the absolute value of chromatic dispersion during compensation of the chromatic dispersion of a 1.3 &mgr;m single-mode optical fiber serving as the target of compensation is 0.5 ps/nm/km or less.

By limiting the ranges of the numerical values of a plurality of structural parameters of a dispersion compensating optical fiber which is endowed with a segmented W-shaped refractive index profile, and by suitably combining these structural parameters, it is possible to obtain a dispersion compensating optical fiber which can compensate both for chromatic dispersion and also for dispersion slope of a single mode optical fiber for transmission over a wide wavelength band which is selected from the range from 1.53 &mgr;m to 1.63 &mgr;m, and for which the value of Aeff is large, and moreover the absolute value of chromatic dispersion is large. As a result desirable transmission characteristics are obtained by being able to suppress the occurrence of nonlinearity effects, and furthermore, since the length which is required is short, the cost is low, and it is possible to produce a module which is small in size.

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Sakura, Japan

Takaaki Suzuki