Multimode fiber having improved index profile

Abstract

A graded index multimode fiber and method of producing the graded index multimode fiber utilize a technique of reducing an index profile of the core of the multimode fiber below a standard parabolic index profile. This can be done by changing dopant concentrations in the fiber core over the radius of the fiber core. The result is a multimode fiber having differential mode delay characteristics that are intentionally not minimized. The index profile can be reduced below the standard parabolic index profile over the entire radius of the core, or only for radii above a specified radius.

1 . A method of manufacturing multimode optical fiber having a core with an index profile resulting in a radius-dependent graded index of refraction, said method comprising reducing the index of refraction over the radius of the fiber core such that the index profile of the fiber core is reduced below a standard parabolic index profile at increasing core radii. 
   
   
       2 . The method of  claim 1  wherein said index profile of said fiber core is decreased below a standard parabolic index profile continuously and monotonically over the radius of the fiber core. 
   
   
       3 . The method of  claim 1  wherein said index profile of said fiber core is reduced below a standard parabolic index profile for core radii greater than 5 μm. 
   
   
       4 . The method of  claim 1  wherein said index profile of said fiber core is reduced below a standard parabolic index profile for core radii greater than 1 μm. 
   
   
       5 . A method of manufacturing multimode optical fiber having a core with an index profile resulting in a radius-dependent graded index of refraction, said method comprising reducing the index of refraction over the radius of the fiber core by controlling dopant concentrations such that the index profile of the fiber core is reduced below a standard parabolic index profile at increasing core radii by reducing a target value of the index profile below a standard parabolic index profile. 
   
   
       6 . The method of  claim 5  wherein said index profile of said fiber core is decreased below a standard parabolic index profile continuously and monotonically over the radius of the fiber core. 
   
   
       7 . The method of  claim 5  wherein said index profile of said fiber core is reduced below a standard parabolic index profile for core radii greater than 5 μm. 
   
   
       8 . The method of  claim 5  wherein said index profile of said fiber core is reduced below a standard parabolic index profile for core radii greater than 1 μm.