An X-ray absorption study of doped silicate glass, fibre optic preforms
Bowron, Daniel Timothy
Newport, Robert J.
Rigden, Jane S.
Optical fibre preforms, which have their germanosilicate core regions doped with small quantities of the rare-earth element erbium, have been studied using Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) at the germanium K absorption edge. These studies were performed using a circular X-ray beam of 100 mu m diameter, allowing information to be gathered as a radial function of position across the core region of the preform. This positioning was accomplished by means of a motorized pinhole collimator and sample stage developed for use on the focused X-ray beamline 8.1, at the SRS, Daresbury Laboratory, UK. The EXAFS results are consistent with the germanium sites coordinated to surrounding oxygen atoms at a mean distance of 0.17 nm. Absorption maps of the rare-earth and germanium distribution across the core region of the preforms have also been obtained, showing a correlation between the distributions of the two atom types.