Patent ID: 8977096
Filing Date: 2015-03-10
Classification: G02B

Abstract:
1. An optical fiber comprising: a glass optical fiber, made from silica glass, comprising: the second core has a refractive index lower than that of the cladding, the optical fiber has an effective core area ≧175 μm the glass optical fiber comprises a primary medium portion and secondary medium portions having a refractive index lower than that of the primary medium portion, the secondary medium portions have a plurality of first secondary medium portions around the first core and a plurality of second secondary medium portions around the first core and outside of the first secondary medium portions a relative refractive index difference Δ six of the first secondary medium portions are positioned such that they create a six-fold rotational symmetry with respect to the first core and a ratio z the second secondary medium portions are positioned outside of the first secondary medium portions such that they create a six-fold rotational symmetry with respect to the first core, six of the second secondary medium portions being positioned on apexes of a hexagon where the apexes are positioned on extension lines of a center of the first core and centers of the first secondary medium portions, other six of the second secondary medium portions being positioned on midpoints of sides of the hexagon.