Patent ID: 7536074

Claim:
An optical fiber made of silica-based material, comprising: a core formed at a center of the optical fiber; and a cladding formed around the core, wherein the core is doped with germanium dioxide, which increases refractive index and decreases acoustic-wave velocity, and aluminum oxide, which increases both refractive index and acoustic-wave velocity, satisfying −2.814+0.594 ×W 1 ≦W 2 ≦54.100+0.218 ×W 1 , W 1 +W 2 ≦60, and W 2 ≧56.63−2.04× W 1 where W 1 is doping amount of germanium dioxide in weight percentage, which is larger than 4.74, and W 2 is doping amount of aluminum oxide in weight percentage, and a nonlinear coefficient of the optical fiber is equal to or larger than 2.6×10 −9 W −1 .