High performance single mode waveguide
 Disclosed is a single mode optical waveguide fiber having a segmented core design. In particular, the core comprises three segments, each having characteristic dimensions and refractive index profile. By proper choice of index profile in each segment, a waveguide fiber is made which has a mode field diameter of about 9.5, low, positive total dispersion over the operating window 1530 nm to 1565 nm as well as effective area greater than 60 .mu.m.sup.2. 
Corning Incorporated
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David K. Ming-Jun Daiping Yanming
Smith Li Ma Liu