Fitel USA Corporation

Stig Nissen Knudsen

Lars Gruner-Nielsen

Morten Ostergaard Pedersen

Robert M Atkins

Poul Kristensen

Alice Weimin Liu

Torben Erik Veng

Kai H Chang

Jake Bromage

Bent Edvold

Morten Østergaard Pedersen

Jan Levin Nielsen

Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.

Method of making optical fiber with reduced E-band and L-band loss peaks

An inverse dispersion fiber is provided that has a relatively low fiber loss, a relatively low fiber splice loss and a relatively large effective mode-field area. The inverse dispersion fiber includes a doped core region with an index of refraction n , a cladding region with an index of refraction n , and a trench region, a first barrier region and a second barrier region with indices of refraction n , n , and n , respectively, formed between the doped core region and the cladding region. The various regions of the inverse dispersion fiber are manufactured in such a way that the refractive index value ranges are, for example, approximately 0.709%<(n &minus;n )/n <1.0%, approximately &minus;0.358%<(n &minus;n )/n <&minus;0.293%, approximately 0.194%<(n &minus;n )/n <0.237%, and approximately &minus;0.045%<(n &minus;n )/n <&minus;0.037%. The inverse dispersion fiber in accordance with the preferred embodiment has a chromatic dispersion of approximately &minus;44 picosecond/(nanometer-kilometer) and a relatively large effective core area, A , that is, for example, greater than approximately 30.0 &mgr;m , both at a wavelength of 1550 nm.

Inverse dispersion compensating fiber

Embodiments of the invention include an optical communications system with optical fiber cable, coupled between optical transmission and receiving devices, having positive dispersion fiber and corresponding inverse dispersion fiber. The inverse dispersion fiber includes a doped core region with an index of refraction n , a cladding region with an index of refraction n , and a trench region, a first barrier region and a second barrier region with indices of refraction n , n , and n , respectively, formed between the doped core region and the cladding region. The various regions of the inverse dispersion fiber are manufactured in such a way that the refractive index value ranges are, e.g., 0.745%<(n &minus;n )/n <0.759%,&minus;0.403%<(n &minus;n )/n <&minus;0.394%, 0.152%<(n &minus;n )/n <0.166%, and &minus;0.083%<(n &minus;n )/n <&minus;0.041%. Inverse dispersion fiber has a chromatic dispersion of approximately &minus;40 picosecond/(nanometer-kilometer) and a relatively large effective core area, A , e.g., greater than approximately 30.0 &mgr;m , both at a wavelength of 1550 nm.

Optical fiber having negative dispersion, negative dispersion slope and large effective area

A dispersion compensating fiber is described having a core and cladding as well as methods for making such fiber. The cladding has a first cladding region surrounding the core, a second cladding region surrounding the first cladding region, and a third cladding region surrounding the second cladding region. The core, and the first, second, and third cladding regions are doped to create a refraction index profile characteristic of dispersion compensating fiber. The core is doped with germanium, the first cladding region is doped with fluorine, and the second cladding region is doped with germanium and fluorine. A portion of the cladding is doped with phosphorus, thereby resulting in splice loss reduction.

Dispersion compensating fiber with reduced splice loss and methods for making same

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Fredriksberg, Denmark

Stig Nissen Knudsen