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 . Method of selecting between a first fiber and a second fiber comprising:
 measuring a pulse delay for pulses traveling through different radii for the first fiber and the second fiber; and   choosing between the first fiber and the second fiber a fiber which demonstrates a greater left shift for radii greater that a predetermined radius.   
     
     
         2 . Method of selecting between a first fiber and a second fiber comprising:
 measuring a pulse delay for pulses traveling through different radii for the first fiber and the second fiber; and   choosing between the first fiber and the second fiber a fiber which has a smaller pulse delay for a pulse at a predetermined radius.   
     
     
         3 . Method of selecting between a first fiber and a second fiber comprising:
 measuring a pulse delay for pulses traveling through different radii for the first fiber and the second fiber; and   choosing between the first fiber and the second fiber a fiber which demonstrates smaller pulse delays for radii greater than a predetermined radius.