Patent ID: 8743454

Claim:
An optical amplifier comprising: at least one pump source and an optical fibre cable; wherein the optical fibre cable comprises an amplifying optical fibre and a pump optical fibre that are defined by respective lengths, and the amplifying optical fibre and the pump optical fibre are coated with a common coating along a portion of their respective lengths; the amplifying optical fibre and the pump optical fibre are in optical contact with each other along a coating length within the common coating; the common coating has a refractive index which is lower than a refractive index of a cladding material of the pump optical fibre; the amplifying optical fibre and the pump optical fibre are made substantially from glass; the amplifying optical fibre comprises a core and a cladding; the amplifying optical fibre is doped with a rare earth dopant; the pump optical fibre is defined by a first end and a second end; and the first end of the pump optical fibre is connected to the pump source.