Optical fiber

摘要

This invention concerns a large-diameter optical fiber that is improved in the bandwidth and bending loss and that can be produced at low cost with higher productivity. The optical fiber comprises an inner core having a refractive index profile in which refractive indices increase toward the center axis thereof, an outer core provided outside the inner core and having a constant refractive index not more than the minimum refractive index of the inner core, and a cladding provided outside the outer core and containing a plastic material having a refractive index lower than that of the outer core. In the optical fiber, total refractive index difference ( DELTA ntotal), defined as the difference between the maximum refractive index of the inner core and the refractive index of the cladding, is not less than 0.015 and not more than 0.1; and a outside core diameter of the outer core (d1) is not less than 100 mu m and not more than 500 mu m.