| 摘要 |
A large core photonic crystal fibre (4) for transmitting radiation having a core (7) comprising a substantially transparent core material and having a core diameter of at least 5 mu m. The fibre also comprises a cladding region surrounding the length of core material, wherein the cladding region comprises a first substantially transparent cladding material, having a first refractive index, and wherein the first substantially transparent cladding material has embedded along its length a substantially periodic array of holes (6), wherein the holes are filled with a second cladding material having a second refractive index less than the first refractive index, such that radiation input to the optical fibre is transmitted along the length of the core material in a single mode of propagation. In a preferred embodiment, the core diameter may be at least 20 mu m, and may be as large as 50 mu m. The fibre is capable of transmitting higher power radiation than conventional fibres, whilst maintaining propagation in a single mode. <??>The core material may doped with a material capable of providing amplification under the action of pump radiation input to the fibre. The invention also relates to a fibre amplifier and a fibre laser comprising a doped large core photonic crystal fibre. The fibre may also be used in a system for transmitting radiation comprising a plurality of lengths of large core photonic crystal fibre, separated by large core photonic crystal fibre amplifiers, such that the power of radiation transmitted through the system is maintained above a predetermined threshold power. <IMAGE> <IMAGE> |
