Multi-fibre arrangement for high power fibre lasers and amplifiers

A method of producing an amplifying optical device comprising a first pump source, at least one pump optical fibre section and at least one amplifying optical fibre section, which amplifying optical device is such that:

• the pump optical fibre section and the amplifying optical fibre section are coated with a common coating material, and are in optical contact, along a portion of their length, and
• the pump optical fibre section and the amplifying optical fibre section are made substantially from glass,
• the method comprising:
• drawing a single composite fibre comprising a pump optical fibre and an amplifying optical fibre each defined by an outside longitudinally extending surface, and wherein the outside longitudinally extending surfaces are in optical contact with each other;
• coating the single composite fibre with the common coating material in a fibre drawing process;
• obtaining the amplifying optical fibre section and the pump optical fibre section from the single composite fibre;
• removing the coating material from two opposite end portions of each of the pump optical fibre section and the amplifying optical fibre section;
• separating each of the two end portions of the pump optical fibre section from the corresponding end portions of the amplifying optical fibre section;
• and
• connecting one of the separated end portions of the pump optical fibre section to the first pump source.