Patent ID: 6631233
Filing Date: 2003-10-07
Classification: B29D,G02B

Abstract:
A graded index type optical fiber having a multilayer structure, comprising:a plurality of concentrically arranged layers, each of said layers being formed of one (co)polymer selected from the group consisting of two or more (homo)polymers HP1, HP2, . . . Hpn, wherein n is an integer of 2 or greater, derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more copolymers derived from said monomers, said multilayer structure being such that the refractive index is highest at the center of the fiber and decreases gradually toward the outer periphery of the fiber, wherein each of the concentrically arranged layers is formed of a (co)polymer having a refractive index nâ€²j (j=1,2,3 . . . ) and is positioned in the cross-sectional area of the fiber by its radial position rj, which expresses the distance from the center of the fiber outward to the position of the layer in the fiber, rj being defined by the equation: rj=&agr;a[{1-(nâ€²j/n1)2}/2&Dgr;]0.5wherein &agr; is the ratio of the diameter of the spinning nozzle from which the fiber is prepared to the diameter of the optical fiber, a is the radius of the optical fiber, n1 is the refractive index at the center, n2 is the refractive index at the outer periphery and &Dgr; is (n1-n2)/n1.