Patent ID: 6031956
Filing Date: 2000-02-29
Classification: G02B

Abstract:
A single mode optical waveguide fiber comprising:a core glass region comprising a first circular central segment, having a relative index .DELTA..sub.0 % and a radius r.sub.0, a first annular segment surrounding and in contact with the central segment, having a relative index .DELTA..sub.1 % and a radius r.sub.1, and a second annular segment surrounding and in contact with the first annular segment, having a relative index .DELTA..sub.2 %, a radius r.sub.2, and a width w.sub.2, the respective segments each having a refractive index profile;a clad glass layer having a refractive index profile and a minimum refractive index n.sub.c, wherein n.sub.c is the reference index for the relative index of each core segment;in which the index profile of the central segment is an a profile having .alpha. in the range of about 0.7 to 2, the index profile of the first annular segment is substantially flat, the index profile of the second annular segment is a rounded step, and .DELTA..sub.0 %>.DELTA..sub.2 %>.DELTA..sub.1 %,the values of the respective .DELTA.'s and radii being chosen so that the inner profile volume is in the range 2.28 to 3.26% .mu.m.sup.2, the outer profile volume is in the range 3.70 to 13.75% .mu.m.sup.2 and the ratio of outer to inner volume is in the range 1.5 to 4.3.