简介 |
An optical amplification fibre is provided with at least one core part to which a rare earth element is added, an inside cladding part that surrounds the core part and that has a refractive index lower than the maximum refractive index of each of the core parts, and an outside cladding part that surrounds the inside cladding part and that has a refractive index lower than the refractive index of the inside cladding part, the inside cladding part having a refractive index difference region in which the refractive index is different to that of the adjacent region. |