Doped Photonic Crystal Fibres - Enhanced possibilities for modification of propagation and for improved application of microstructured fibres

Photonic crystal fibres (PCF) are typically made of pure (undoped) silica glass. An exception are rare earth doped microstructured laser fibres, mostly with air clad design. The use of different materials as stacking elements, i.e. capillaries and rods with radial index profile, create extended posibilities for the variation of optical behaviour of microstructured fibres. Capillaries doped with germanium, phosphorus and fluorine were prepared by MCVD technique. The optical properties of the doped PCFs (i.e. mode field distribution, numerical aperture, bending loss) were investigated and compared with undoped PCFs.