Graded index optical fibre

摘要

Disclosed is a graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged non-blended layers LNB1 to LNBm formed of (co)polymers P1 to Pm selected from the group consisting of two or more homopolymers HP1, HP2, ... and HPn composed of units of vinyl monomers M1, M2, ... and Mn, respectively (provided that the refractive indices of the homopolymers decrease in that order), and one or more binary copolymers CPs composed of units of vinyl monomers M1, M2, ... and Mn, each of (co)polymers P1 to Pm having a glass transition temperature (Tg) of 80 DEG C or above, wherein the refractive index is highest at the center of the multilayer structure and decreases gradually toward the outer periphery thereof. This optical fiber has a small transmission loss, a large numerical aperture, and excellent resistance to moist heat. <IMAGE>