Optical fiber for WDM system and manufacturing method thereof

Abstract

An optical fiber having a length of 1 km or more with average transmission loss in a wavelength band of 1383 nm being less than average transmission loss in a wavelength band of 1310 nm, wherein a maximum value of any 1 km section loss in the wavelength band of 1383 nm does not exceed the average transmission loss by 0.03 dB/km or more.

1 - 10 . (canceled)  
   
   
       11 . A manufacturing method of an optical fiber having a mode field diameter of 8.0 to 11.0 μm at a wavelength of 1310 nm, an average transmission loss at a wavelength of 1383 nm less than an average transmission loss at a wavelength of 1310 nm, and a dispersion of +2 to +8 ps/nm/km at the wavelength of 1383 nm, comprising the steps of 
 drawing the optical fiber from an optical fiber preform, applying coating resins on said optical fiber, and    exposing said optical fiber to a deuterium containing atmosphere.    
   
   
       12 . The manufacturing method of an optical fiber according to  claim 11 , wherein the optical fiber has a dispersion of +4 to +7 ps/nm/km at a wavelength of 1383 nm.  
   
   
       13 . The manufacturing method of an optical fiber according to  claim 11 , wherein said step of exposing is performed by exposing the optical fiber to the deuterium containing atmosphere under an ordinary pressure at an ordinary temperature.  
   
   
       14 . The manufacturing method of an optical fiber according to  claim 13 , wherein the exposing time in said step of exposing is 24 hours at longest.  
   
   
       15 . The manufacturing method of an optical fiber according to  claim 11 , wherein an increase in transmission loss at the wavelength of 1383 nm after hydrogen ageing is 0.04 dB/km or less.  
   
   
       16 . The manufacturing method of an optical fiber according to  claim 11 , wherein an increase in transmission loss at the wavelength of 1383 nm after hydrogen ageing is 0.01 dB/km or less.  
   
   
       17 . A manufacturing method of an optical fiber, including an exposing step of exposing the optical fiber after drawing to a deuterium containing atmosphere, wherein a difference between average transmission losses respectively at the wavelengths of 1385 nm and 1420 nm before said exposing step becomes different from a difference between average transmission losses respectively at the wavelengths of 1385 nm and 1420 nm after said exposing step, by 0.01 dB/km or more at least one time.  
   
   
       18 . The manufacturing method of an optical fiber according to  claim 17 , wherein a time interval from the time point at which said deuterium processing is started to the time point at which said transmission loss is measured is 48 hours or more at 25° C.  
   
   
       19 . The manufacturing method of an optical fiber according to  claim 17 , wherein the length of the optical fiber is 10 km or more and a cable cutoff wavelength at a length of 22 m of 1300 nm or less.  
   
   
       20 . A manufacturing method of an optical fiber, comprising the steps of 
 drawing the optical fiber from an optical fiber preform, winding said optical fiber around a bobbin, and then immediately exposing said optical fiber to a deuterium containing atmosphere, wherein    said optical fiber is rewound around another bobbin while applying tensile tension, before said deuterium is completely degassed from said optical fiber.    
   
   
       21 . The manufacturing method of an optical fiber according to  claim 20 , wherein said tensile tension corresponds to 0.5% to 2% in tensile strain of the optical fiber.  
   
   
       22 . The manufacturing method of an optical fiber according to  claim 20 , wherein said optical fiber is cut and divided into predetermined lengths in the longitudinal direction when said optical fiber is rewound.