Method for the manufacture of optical fibers and improved optical fibers

Abstract

The specification describes a universal channel dispersion compensating fiber (CDCF) for WDM channel compensation that provides essentially zero dispersion slope over the wide wavelength band used in state-of-the-art transmission systems. It allows compensation of a large number of channels using a single fiber design. The improved optical fiber of the invention exhibits a dispersion slope at 1550 nm: <0.02 ps/nm 2 -km, preferably <0.01 ps/nm 2 -km, and a maximum variation of dispersion per km over the S-, C-, and L-bands of preferably less than 2.0 Ps. In a preferred embodiment, the index profile of these fibers comprises a simple three layer design, i.e. an up-doped central core, surrounded by a down-doped trench region, further surrounded by an up-doped ring region.

1 . An optical fiber characterized by: 
 (a) dispersion at 1550 nm: <−20 ps/nm-km,    (b) −0.02 ps/nm 2 -km<dispersion slope at 1550 nm<0.02 ps/nm 2 -km, and wherein the normal optical energy confinement region consists essentially of a central core region, a trench region, and a ring region.    
     
     
         2 . The optical fiber of  claim 1  wherein the dispersion 
 at 1550 nm: <−40 ps/nm-km  
 
     
     
         3 . The optical fiber of  claim 1  wherein: 
 −0.01 ps/nm 2 -km<Dispersion slope at 1550 nm<0.01 ps/nm 2 -km.  
 
     
     
         4 . The optical fiber of  claim 1  wherein the dispersion over the wavelength region of 1500 nm to 1620 nm is less than 5 ps/km.  
     
     
         5 . The optical fiber of  claim 1  wherein the dispersion over the wavelength region of 1500 nm to 1620 nm is less than 2 ps/km.  
     
     
         6 . The optical fiber of  claim 1  further characterized by: 
 Cutoff wavelength: <1470 nm  
 Polarization Mode Dispersion (PMD): 0.02-0.06 ps/km 2    
 Attenuation @ 1550 nm: <0.4 dB/km  
 
     
     
         7 . The optical fiber of  claim 1  additionally including a second trench region outside of the normal optical energy confinement region.  
     
     
         8 . An optical fiber characterized by: 
 (a) dispersion at 1550 nm: <−40 ps/nm-km,    (b) −0.01 ps/nm 2 -km<Dispersion slope at 1550 nm<0.01 ps/nm 2 -km,    (c) dispersion over the wavelength region of 1500 nm to 1620 nm: less than 2 ps/km,    and wherein the normal optical energy confinement region consists essentially of a central core region, a trench region, and a ring region.    
     
     
         9 . The optical fiber of  claim 8  wherein the dispersion slope is positive.  
     
     
         10 . The optical fiber of  claim 8  additionally including a second trench region outside of the normal optical energy confinement region.  
     
     
         11 . An optical WDM system comprising: 
 a. a length of optical fiber,    b. lightwave signal source for introducing a lightwave signal into the optical fiber, the lightwave signal comprising multiple wavelength division multiplexed (WDM) wavelengths,    c. demultipler for separating the lightwave signal into multiple demultiplexed channels,    d. dispersion compensator in each demultiplexed channel, the dispersion compensator comprising a length of channel dispersion compensating fiber (CDCF), the CDCF comprising an optical fiber characterized by: 
 (i) dispersion at 1550 nm: <−20 ps/nm-km,  
 (ii) −0.02 ps/nm 2 -km<dispersion slope at 1550 nm<0.02 ps/nm 2 -km,  
 (iii) dispersion over the wavelength region of 1500 nm to 1620 nm: less than 2 ps/km,  
   and wherein the normal optical energy confinement region consists essentially of a central core region, a trench region, and a ring region.    
     
     
         12 . The system of  claim 11  wherein the CDCF in each of the demultiplexed channels have essentially the same refractive index profile.  
     
     
         13 . The system of  claim 12  wherein the CDCF in each of the demultiplexed channels have different lengths.  
     
     
         14 . The system of  claim 11  wherein the lightwave signal includes wavelengths above 1510 nm, and includes 1550 nm.  
     
     
         15 . The system of  claim 11  wherein the multiple wavelength division multiplexed (WDM) wavelengths operate over the C-, L- or extended L-bands.  
     
     
         16 . The system of  claim 15  wherein the lightwave signal operates at 40 Gb/s.  
     
     
         17 . The system of  claim 11  wherein the dispersion of the CDCF at 1550 nm: <−40 ps/nm-km.  
     
     
         18 . The system of  claim 17  wherein the dispersion slope of the CDCF is: 
 -0.01 ps/nm 2 -km<Dispersion slope at 1550 nm<0.01 ps/nm 2 -km.  
 
     
     
         19 . The system of  claim 18  wherein the dispersion of the CDCF over the wavelength region of 1500 nm to 1620 nm is less than 5 ps/km.  
     
     
         20 . The system of  claim 18  wherein the dispersion of the CDCF over the wavelength region of 1500 nm to 1620 nm is less than 2 ps/km.  
     
     
         21 . The CDCF of the system of  claim 11  further characterized by: 
 Cutoff wavelength: <1470 nm  
 Polarization Mode Dispersion (PMD): 0.02-0.06 ps/km 2    
 Attenuation @ 1550 nm: <0.4 dB/km  
 
     
     
         22 . The CDCF of the system of  claim 11  additionally including a second trench region outside of the normal optical energy confinement region.  
     
     
         23 . The system of  claim 11  wherein the dispersion slope of the CDCF is positive.