Abstract: This dispersion compensating optical fiber comprises an uncovered dispersion compensating optical fiber which contains a core and a cladding and a resin coating which is disposed around the uncovered dispersion compensating optical fiber and which has an adhesive property of 10 g/mm or less. Alternatively, the dispersion compensating optical fiber comprises an uncovered dispersion compensating optical fiber which contains a core and a cladding and a resin coating which is disposed around the uncovered dispersion compensating optical fiber, which has an adhesive property of 1 g/mm or less, and which includes a single or double coating layer and an outer coating layer formed on the surface of the single or double coating layer to have a thickness of 3 &mgr;m or more.

Abstract: 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.

Abstract: 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.

Abstract: In a wavelength division multiplexed transmission path, the used waveband can be selected from the widest possible waveband among the S-band, C-band, and L-band. The wavelength division multiplexed transmission path has a dispersion-compensating transmission path comprising a dispersion-shifted fiber, which has positive chromatic dispersion throughout a range of wavelengths from 1460 nm to 1630 nm, and one type of dispersion-compensating fiber, or two or more types of dispersion-compensating fiber having different chromatic dispersion having negative chromatic dispersion in a compensation waveband, selected from the abovementioned range; the residual chromatic dispersion of the wavelength division multiplexed transmission path is adjusted so as to be greater than −1.0 ps/nm/km or equal to and less than or equal to +1.0 ps/nm/km in a used waveband of the wavelength division multiplexed transmission path, which is selected from the abovementioned range.

Abstract: 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.

Abstract: The present invention is related to an dispersion compensating optical fiber technology, comprising a central core, a middle part with a refractive index lower than this central core, and a cladding with a refractive index higher than said middle part and lower than said central core, characterized in: an outer diameter of said middle part being 2.5.about.3.5 times an outer diameter of said central core; a relative refractive index difference of said cladding to said middle part being -0.08.about.-0.2% with the refractive index of the cladding being zero; and having substantially single-mode transmission in the wavelength 1.55 .mu.m band, the chromatic dispersion being -80 ps/nm/km or less, the dispersion slope being +0.08 ps/nm.sup.2 /km or less, and the bending loss being 1.0 dB/m or less.

Abstract: The polarization-maintaining optical fiber 10 of the present invention is designed so that a plurality of core portions 12a,12b which have a high refractive index is provided in parallel along a single diameter direction in the cross section of the optical fiber, these core portions 12a,12b cooperating to propagate a single fundamental mode. In the production method for the polarization-maintaining optical fiber of the present invention, a plurality of holes 22 are formed longitudinally in parallel along a single diameter direction of a glass rod 21 having a low refractive index which forms the cladding, glass rods 23 for core use having a high refractive index which form the core portions are inserted into these holes 22, heating to form a unitary body is carried out, creating a preform which is then drawn.