Dispersion compensating optical fiber

An optical communication system in which a dispersion compensating optical fiber is optically coupled to an optical transmission line of an optical fiber having substantially zero dispersion at a transmission wavelength of 1,300 nm, said dispersion compensating optical fiber being a single mode optical waveguide type dispersion compensating optical fiber having a W-shaped three layer refractive index profile, comprising:

• a first generally cylindrical core layer of radius a.sub.1 and refractive index n.sub.1 ;
• a second generally hollow cylindrical core layer of external radius a.sub.2 and refractive index n.sub.2 formed on the outside of said first core layer and generally coaxial therewith;
• and
• a generally hollow cylindrical cladding layer of refractive index n.sub.3 formed on the outside of said second core layer and generally coaxial with both said first and second core layers;
• wherein:
• 2.5<a.sub.2 /a.sub.1 .ltoreq.4;
• n.sub.1 >n.sub.3 >n.sub.2 ;
• the proportional refractive index difference of said core layer with respect to said cladding layer as expressed by {(n.sub.1.sup.2 +n.sub.3.sup.2)/2n.sub.1.sup.2)}.times.100, is between approximately 1.6% and approximately 2.1%;
• and
• the proportional refractive index difference of said second core layer with respect to said cladding layer as expressed by {(n.sub.2.sup.2 -n.sub.3.sup.2 /2n.sub.2.sup.2)}.times.100, is between approximately -0.60% and approximately -0.45%;
• whereby the dispersion compensation ratio, obtained by dividing the ratio of the dispersion slope of this dispersion compensating optical fiber to the dispersion slope of a single mode optical fiber from a wavelength of 1,530 nm to a wavelength of 1,570 nm, by the ratio of the dispersion value of this dispersion compensation optical fiber to the dispersion value of a single mode optical fiber at a wavelength of 1,550 nm, is between approximately 0.75 to approximately 1.25.

A single mode dispersion compensating optical fiber having a three layer W-shaped refractive index profile, comprising:

• a first generally cylindrical core layer of radius a.sub.1 and having a refractive index n.sub.1 ;
• a second generally hollow cylindrical core layer of external radius a.sub.2 and having a refractive index n.sub.2 formed on the outside of said first core layer and generally coaxial therewith;
• and
• a generally hollow cylindrical cladding layer of refractive index n.sub.3 formed on the outside of said second core layer and generally coaxial with both said first and said second core layers,
• wherein a.sub.2 /a.sub.1 is between approximately 2.5 and approximately 4;
• n.sub.1 >n.sub.3 >n.sub.2 ;
• the proportional refractive index difference of said first core layer with respect to said cladding layer, as expressed by {(n.sub.1.sup.2 -n.sub.3.sup.2)/2n.sub.1.sup.2)}.times.100 is between approximately 1.6% and approximately 2.1%,
• the proportional refractive index difference of said second core layer with respect to said cladding layer, as expressed by {(n.sub.2.sup.2 -n.sub.3.sup.2)/2n.sub.2.sup.2)}.times.100, is between approximately -0.60% and approximately -0.45%, and
• whereby the dispersion slope compensation ratio, obtained by dividing the ratio of the dispersion slope of this dispersion compensating optical fiber to the dispersion slope of a single mode optical fiber from a wavelength of 1530 nm to a wavelength of 1570 nm, by the ratio of the dispersion value of this dispersion compensating optical fiber to the dispersion value of a single mode optical fiber at a wavelength of 1550 nm, is between approximately 0.75 and approximately 1.25.