Patent ID: 7046433

Claim:
An optical fiber having a plurality of glass layers and a dispersion of −8 ps/nm/km or less at a wavelength of 1460 nm, wherein; a composition of one of said plurality of glass layers is different from a composition of glass layers adjacent to said one glass layer; said plurality of glass layers comprises a reference layer to be referenced for a refractive index profile and at least three glass layers provided on the inside of said reference layer; and, Δ 1 >Δ 3 >Δ 2 , Δ 1 ≧1.0% and ΔC<0 are satisfied wherein Δ 1 is the maximum relative refractive index difference of the first glass layer formed innermost of said at least three glass layers with respect to said reference layer, Δ 2 is the relative refractive index difference of the second glass layer formed second from the inside with respect to said reference layer, Δ 3 is the relative refractive index difference of the third glass layer formed third from the inside with respect to said reference layer, and ΔC is the relative refractive index difference of said reference layer with respect to pure quartz glass, wherein conditions 1.0%≦Δ 1 ≦3.0%, −1.0%≦Δ 2 ≦−0.4%, 0%<Δ 3 ≦0.5% are also satisfied.