Local order around Rare Earth elements in optic fibres.

Rare Earth elements (Er, Yb) are added to the composition of the core of optic fibers for their luminescent properties that permit the realization of 'in fibre' optical amplfiers. The local structure around these elements (either crystalline or amorphous) can determine the luminescent properties in terms of intensity and lineshape. This experiment will be conducted on single fibres drawn at different temperature values with the aim of establishing a link with the local order. The experiment will be carried out at the L3 edges of Er and Yb