Optical fiber.

摘要

An optical fiber comprising a core (11) at least a center portion of which is made of glass essentially consisting of silica, a first cladding (12) which is provided around the core (11) and has a refractive index smaller than that of the core (11) and a second cladding (13) which is provided around the first cladding (12) and has a refractive index larger than that of the first cladding (12) and lower than that of the core (11), which has improved environmental resistance and small wavelength dispersion in a wide range of wavelength.