Optical fiber and optical transmission system including the same

Abstract

The present invention relates to an optical fiber which enables favorable optical communications in 1.3-μm and 1.55-μm wavelength bands, and an optical transmission system including the same. The optical fiber according to the present invention has only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, the zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.50 μm, and has a positive dispersion slope at the zero-dispersion wavelength, thereby enabling favorable optical communications utilizing each signal light in the 1.3-μm and 1.55-μm wavelength bands sandwiching the zero-dispersion wavelength.

What is claimed is:  
     
         1 . An optical fiber having only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, 
 said zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.50 μm,  
 said optical fiber having a positive dispersion slope at said zero-dispersion wavelength and an effective area of greater than 60 μm 2  at a wavelength of 1.55 μm.  
 
     
     
         2 . An optical fiber according to    claim 1   , wherein said dispersion slope has an absolute value of 0.10 ps/nm 2 /km or less.  
     
     
         3 . An optical fiber according to    claim 1   , wherein said optical fiber has a dispersion slope of 0.06 ps/nm 2 /km or less at the wavelength of 1.55 μm.  
     
     
         4 . An optical fiber according to    claim 1   , wherein an absolute value of dispersion at the wavelength of 1.55 μm is 12 ps/nm/km or less.  
     
     
         5 . An optical fiber according to    claim 1   , wherein the absolute value of dispersion at the wavelength of 1.55 μm m is 6 ps/nm/km or more.  
     
     
         6 . An optical fiber according to    claim 5   , wherein an absolute value of dispersion at a wavelength of 1.30 μm is 6 ps/nm/km or more but 12 ps/nm/km or less.  
     
     
         7 . An optical fiber according to    claim 1   , wherein said optical fiber has a bending loss which becomes 0.5 dB/turn or less at a wavelength of 1.55 μm when wound at a diameter of 32 mm.  
     
     
         8 . An optical fiber according to    claim 7   , wherein said optical fiber has a bending loss which becomes 0.06 dB/turn or less at a wavelength of 1.55 μm when wound at a diameter of 32 mm.  
     
     
         9 . An optical fiber according to    claim 1   , wherein said optical fiber has a cutoff wavelength of 1.05 μm or more.  
     
     
         10 . An optical fiber according to    claim 9   , wherein said optical fiber has a cutoff wavelength of 1.30 μm or more.  
     
     
         11 . An optical fiber according to    claim 1   , wherein an increase in transmission loss caused by OH absorption at a wavelength of 1.38 μm is 0.1 dB/km or less.  
     
     
         12 . An optical fiber according to    claim 1   , wherein said optical fiber has a refractive index profile in which maximum and minimum values of relative refractive index difference with reference to a refractive index of pure silica are 1% or less and −0.5% or more, respectively.  
     
     
         13 . An optical fiber according to    claim 1   , wherein said optical fiber comprises: 
 a core region extending along a predetermined axis and having a predetermined refractive index; and    a cladding region provided on the outer periphery of said core region.    
     
     
         14 . An optical fiber according to    claim 13   , wherein said cladding region comprises an inner cladding, in contact with the outer periphery of said core region, having a lower refractive index than said core region; and, an outer cladding, provided on the outer periphery of said inner cladding, having a refractive index higher than that of said inner cladding and lower than that of said core region.  
     
     
         15 . An optical fiber according to    claim 1   , wherein said optical fiber comprises: 
 a core region which is a region extending along a predetermined axis, and comprising a first core having a predetermined refractive index, and a second core, provided on the outer periphery of said first core, having a lower refractive index than said first core; and    a cladding region provided on the outer periphery of said core region.    
     
     
         16 . An optical fiber according to    claim 15   , wherein said cladding region comprises an inner cladding, in contact with the outer periphery of said second core, having a lower refractive index than said second core; and, an outer cladding, provided on the outer periphery of said inner cladding, having a refractive index higher than that of said inner cladding and lower than that of said second core.  
     
     
         17 . An optical fiber according to    claim 1   , wherein said optical fiber comprises: 
 a core region which is a region extending along a predetermined axis, and comprising a first core having a predetermined refractive index, a second core, provided on the outer periphery of said first core, having a lower refractive index than said first core, and a third core, provided on the outer periphery of said second core, having a higher refractive index than said second core; and    a cladding region provided on the outer periphery of said core region.    
     
     
         18 . An optical fiber according to    claim 17   , wherein said second core has a refractive index equal to or higher than that of said cladding region.  
     
     
         19 . An optical fiber according to    claim 17   , wherein said cladding region comprises an inner cladding, in contact with the outer periphery of said third core, having a lower refractive index than said third core; and, an outer cladding, provided on the outer periphery of said inner cladding, having a refractive index higher than that of said inner cladding and lower than that of said third core.  
     
     
         20 . An optical fiber according to    claim 19   , wherein said second core has a refractive index equal to or higher than that of said outer cladding.  
     
     
         21 . An optical fiber according to    claim 1   , wherein said optical fiber comprises: 
 a core region which is a region extending along a predetermined axis, and comprising a first core having a predetermined refractive index, and a second core, provided on the outer periphery of said first core, having a higher refractive index than said first core; and    a cladding region provided on the outer periphery of said core region.    
     
     
         22 . An optical fiber according to    claim 21   , wherein said cladding region comprises an inner cladding, in contact with the outer periphery of said second core, having a lower refractive index than said second core; and, an outer cladding, provided on the outer periphery of said inner cladding, having a refractive index higher than that of said inner cladding and lower than that of said second core.  
     
     
         23 . An optical fiber according to    claim 1   , wherein said optical fiber comprises: 
 a core region which is a region extending along a predetermined axis, and comprising a first core having a predetermined refractive index, a second core, provided on the outer periphery of said first core, having a higher refractive index than said first core, a third core, provided on the outer periphery of said second core, having a lower refractive index than said second core, and a fourth core, provided on the outer periphery of said third core, having a higher refractive index than said third core; and    a cladding, provided on the outer periphery of said core region, having a lower refractive index than said fourth core.    
     
     
         24 . An optical fiber having only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, 
 said zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.43 μm,  
 said optical fiber having a positive dispersion slope at said zero-dispersion wavelength and an effective area of greater than 50 μm 2  at a wavelength of 1.55 μm.  
 
     
     
         25 . An optical fiber according to    claim 24   , wherein said effective area is greater than 60 μm 2  at the wavelength of 1.55 μm.  
     
     
         26 . An optical fiber according to    claim 24   , wherein said dispersion slope has an absolute value of 0.10 ps/nm 2 /km or less.  
     
     
         27 . An optical fiber according to    claim 24   , wherein said optical fiber has a dispersion slope of 0.06 ps/nm 2 /km or less at a wavelength of 1.55 μm.  
     
     
         28 . An optical fiber according to    claim 24   , wherein an absolute value of dispersion at the wavelength of 1.55 μm is 12 ps/nm/km or less.  
     
     
         29 . An optical fiber according to    claim 24   , wherein the absolute value of dispersion at the wavelength of 1.55 μm is 6 ps/nm/km or more.  
     
     
         30 . An optical fiber according to    claim 24   , wherein an absolute value of dispersion at a wavelength of 1.30 μm m is 6 ps/nm/km or more but 12 ps/nm/km or less.  
     
     
         31 . An optical fiber according to    claim 24   , wherein said optical fiber has a bending loss which becomes 0.5 dB/turn or less at a wavelength of 1.55 μm when wound at a diameter of 32 mm.  
     
     
         32 . An optical fiber according to    claim 31   , wherein said optical fiber has a bending loss which becomes 0.06 dB/turn or less at a wavelength of 1.55 μm when wound at a diameter of 32 mm.  
     
     
         33 . An optical fiber according to    claim 24   , wherein said optical fiber has a cutoff wavelength of 1.05 μm or more.  
     
     
         34 . An optical fiber according to    claim 33   , wherein said optical fiber has a cutoff wavelength of 1.30 μm or more.  
     
     
         35 . An optical fiber according to    claim 24   , wherein an increase in transmission loss caused by OH absorption at a wavelength of 1.38 μm is 0.1 dB/km or less.  
     
     
         36 . An optical fiber having only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, 
 said zero-dispersion wavelength existing within a wavelength range of longer than 1.45 μm but not longer than 1.50 μm,  
 said optical fiber having a positive dispersion slope at said zero-dispersion wavelength.  
 
     
     
         37 . An optical fiber having only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, 
 said zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.50 μm,  
 said optical fiber having a positive dispersion slope at said zero-dispersion wavelength and a bending loss which becomes 0.06 dB/turn or less at a wavelength of 1.55 μm when wound at a diameter of 32 mm.  
 
     
     
         38 . An optical fiber having only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, 
 said zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.50 μm,  
 said optical fiber having a positive dispersion slope at said zero-dispersion wavelength and a cutoff wavelength of 1.05 μm or more.  
 
     
     
         39 . An optical fiber according to    claim 38   , wherein said cutoff wavelength is 1.30 μm or more.