Optical fiber and optical transmission line

Abstract

The optical fiber includes a center core portion, a side core portion and clad portion, which has a dispersion value of 14-20 ps/nm/km at a wavelength of 1550 nm, a dispersion slope of 0.05-0.08 ps/nm 2 /km at a wavelength of 1550 nm and a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, wherein the relative refractive index difference Δ1 between the center core portion and the clad portion is 0.25-0.50%, the relative refractive index difference Δ2 between the side core portion and the clad portion is 0.05-0.30%, an inequality Δ2 <Δ1 is satisfied, the ratio a/b between an outer diameter a of the center core portion and an outer diameter b of the side core portion is 0.3-0.7, and the effective core area Aeff at a wavelength of 1550 nm is 90 μm 2 or larger.

1 - 4 . (Canceled)  
     
     
         5 . An optical fiber which has a dispersion value of 14 ps/nm/km or higher and 20 ps/nm/km or less at a wavelength of 1550 nm, a positive dispersion slope of 0.05 ps/nm 2 /km or higher and 0.08 ps/nm 2 /km or less at a wavelength of 1550 nm, a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, and an effective core area Aeff of 90 μm 2  or larger at a wavelength of 1550 nm.  
     
     
         6 . The optical fiber according to  claim 5 , wherein the effective core Aeff at a wavelength of 1550 nm is 100 μm 2  or larger.  
     
     
         7 . The optical fiber according to  claim 5 , further comprising a center core portion, a side core portion and clad portion in order from an inner side, wherein a relative refractive index difference Δ1 of the center core portion with respect to the clad portion is positive, a relative refractive index difference Δ2 of the side core portion with respect to the clad portion is positive, and an inequality Δ1>Δ2 is satisfied.  
     
     
         8 . The optical fiber according to  claim 6 , further comprising a center core portion, a side core portion and clad portion in order from an inner side, wherein a relative refractive index difference Al of the center core portion with respect to the clad portion is positive, a relative refractive index difference Δ2 of the side core portion with respect to the clad portion is positive, and an inequality Δ1>Δ2 is satisfied.  
     
     
         9 . An optical transmission line comprising: 
 a plurality of optical fibers, each of which configured to transmit an optical signal, wherein at least one of said plurality of optical fibers has a dispersion value of 14 ps/nm/km or higher and 20 ps/nm/km or less at a wavelength of 1550 nm, a positive dispersion slope of 0.05 ps/nm 2 /km or higher and 0.08 ps/nm 2 /km or less at a wavelength of 1550 nm, a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, and an effective core area Aeff of 90 μm 2  or larger at a wavelength of 1550 nm.    
     
     
         10 . An optical transmission line of  claim 9 , wherein the effective core Aeff of said at least one of the plurality of optical fibers at a wavelength of 1550 nm is 100 μm 2  or larger.