Patent ID: 7627220

Claim:
Optical fiber comprising: a central core ( 1 ); a first annular region (ra) surrounding the central core ( 1 ); a second annular region (rb) surrounding the first annular region (ra) and comprising medium-size cavities ( 3 ) the cross section whereof remains strictly between a given first threshold and a given second threshold strictly higher than the first threshold; a third annular region (rc) surrounding the second annular region (rb) and comprising large cavities ( 4 ) the cross section whereof remains strictly above the second threshold; characterized in that, in a cross section of the optical fiber: any radius that goes from the center of the core towards the exterior of the optical fiber encounters at least either a medium-size cavity ( 3 ) in the second annular region (rb) or a large cavity ( 4 ) in the third annular region (rc); and the average distance between the outer perimeter (Ca) of the second annular region (rb) and the inner perimeter (Cb) of the third annular region (rc) is less than half the average dimension of a large cavity ( 4 ); and wherein the optical fiber is characterized in that the arrangement of the cavities in the second annular region (rb) and the arrangement of the cavities in the third annular region (rc) are circular and the arrangement of the cavities in the first annular region (ra) is hexagonal.