Dispersion compensating devices and systems

A silica based dispersion compensating optical waveguide fiber having a material dispersion, and having a reflective index profile preselected to generate negative waveguide dispersion, such that the total dispersion of said fiber, equal to the sum of said material dispersion and said waveguide dispersion is less than -20 ps/nm-km at a given wavelength within the range from 1520 nm to 1565 nm, said fiber attenuating light transmitted along its length, the attenuation of said fiber at said given wavelength being less than 1 dB/km wherein said fiber is designed for single mode transmission at a nominal transmission wavelength and wherein said refractive index profile is preselected to provide a cutoff wavelength located such that said nominal transmission wavelength is approximately midway between said cutoff wavelength and a bend edge wavelength at which a straight fiber will no longer maintain said single mode transmission.

A silica based dispersion compensating optical waveguide fiber having a material dispersion and having a refractive index profile preselected to generate negative waveguide dispersion such that the total dispersion of said fiber, equal to the sum of said material dispersion and said waveguide dispersion, is less than -20 ps/nm-km at a given wavelength within the range from 1520 nm to 1565 nm, and the average slope S.sub.dcf of the total dispersion versus wavelength curve of said fiber in the wavelength range between 1520 nm and 1565 nm is determined by the relationship,

• 0.gtoreq.S.sub.dcf .gtoreq.2D.sub.dcf (S.sub.tf /D.sub.tf)
• where D.sub.dcf is the dispersion of said dispersion compensating fiber, S.sub.tf is the average slope of the total dispersion versus wavelength curve in the wavelength range between 1520 nm and 1565 nm, of a standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, D.sub.tf is the total dispersion of said standard single-mode transmission fiber at a wavelength in the range between 1520 nm and 1565 nm, and D.sub.dcf is within the range from -20 to -120 ps/nm-km.

A silica based dispersion compensating optical waveguide fiber having a material dispersion, and havinq a refractive index profile preselected to generate negative waveguide dispersion such that the total dispersion of said fiber, equal to the sum of said material dispersion and said waveguide dispersion, is less than -20 ps/nm-km at a given wavelength within range from 1520 nm to 1565 nm, the average slope S.sub.dcf of the total dispersion versus wavelength curve of said dispersion compensation fiber in the wavelength range between 1520 nm and 1565 nm is approximately determined by the relationship

• S.sub.dcf =D.sub.dcf (S.sub.tf /D.sub.tf)
• where D.sub.dcf is the dispersion of said dispersion compensation fiber, S.sub.tf is the slope of the total dispersion versus wavelength curve in the wavelength range between 1520 nm and 1565 nm, of a standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, and D.sub.tf is the total dispersion of said standard single-mode transmission fiber at said given wavelength.

A dispersion compensated optical transmission link comprising the serial combination of at least 40 km standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, a dispersion compensating optical waveguide fiber having a refractive index profile preselected to generate negative waveguide dispersion with a length less than about one-half that of said standard single-mode transmission fiber, such that the total dispersion per nm of source spectral width of said dispersion compensated optical transmission link is less than 300 ps/nm at a given wavelength in the wavelength range from 1520 nm to 1565 nm, and optical fiber amplifier means in said link, wherein the loss over said dispersion compensated optical transmission link is less than or equal to the loss due to attenuation over the at least 40 km length of standard single-mode fiber.

A dispersion compensated optical transmission link comprising the serial combination of at least 40 km of silica based standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, and a length of dispersion compensating optical waveguide fiber having a material dispersion and having a refractive index profile preselected to generate negative waveguide dispersion such that the total dispersion of said fiber, equal to the sum of said material dispersion and said wavequide dispersion, is less than -20 ps/nm-km at a given wavelength within the range from 1520 nm to 1565 nm, said fiber attenuatinq liqht transmitted alonq its lenqth, the attenuation of said fiber at said given wavelength is less than 1 dB/km, and the length of said dispersion compensating dispersion compensating fiber is no greater than about one-half that of said standard single-mode transmission fiber.

A dispersion compensated optical transmission link comprising the serial combination of at least 40 km of silica based standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, and a length of dispersion compensating optical waveguide fiber having a refractive index profile preselected to generate negative waveguide dispersion such that the total dispersion of said dispersion compensating fiber is less than -80 ps/nm-km at a given wavelength within the range from 1520 nm to 1565 nm, the average slope of the total dispersion versus wavelength curve in the wavelength range from 1520 nm to 1565 nm being between 0 and -1.2 ps/nm.sup.2 -km, the length of said dispersion compensating fiber being no greater than about one-half that of said standard single-mode transmission fiber.

A dispersion compensated optical transmission link comprising the serial combination of a first length of standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, and a dispersion compensating optical waveguide fiber having a refractive index profile preselected to generate negative waveguide dispersion and having a second length of less than about one-half said first length, such that the Composite Second Order distortion products of said transmission link at a given wavelength in the wavelength range from 1520 nm to 1565 nm are reduced to a level that is approximately the same as the Composite Second Order distortion products of a transmission link comprising a dispersion shifted single-mode fiber optimized for low dispersion operation at said given wavelength and having the same length as said first length.

A dispersion compensator for use with a standard single-mode transmission fiber optimized for low dispersion operation at a wavelength in the range between 1290 nm and 1330 nm, said compensator comprising an optical fiber amplifier connected in series with a dispersion compensating fiber having negative total chromatic dispersion at a given wavelength within the range from 1520 nm to 1565 nm, said optical fiber amplifier providing amplification at said given wavelength.

An optical transmission system comprising an optical source operating at a given wavelength within the range from 1520 nm to 1565 nm, an optical detector, an optical transmission fiber, a dispersion compensating fiber and an optical fiber amplifier serially connected between said source and detector, said transmission fiber being optimized for low dispersion operation at a wavelength in the range from 1290 nm to 1330 nm, said dispersion compensating fiber having a refractive index profile preselected to generate negative waveguide dispersion such that the total dispersion of said fiber is less than -20 ps/nm-km at a given wavelength within the range from 1520 nm to 1565 nm.