Silica fibres activated by YAG : Nd{sup 3+} nanocrystals
We report data on the development of a polymer – salt method for the formation of aluminium yttrium garnet crystals doped with neodymium ions (YAG : Nd) inside the channels of a preform of microstructured fibre based on pure silica glass. The crystals are obtained by impregnating the channels with aqueous solutions of thermally decomposable salts (yttrium nitrate, aluminium nitrate, neodymium chloride) and an organic polymer, followed by drying and heat treatment at a temperature of 1100 °C. The resulting composite structure is drawn into the fibre at a temperature of 2000 °C. Using X-ray diffraction analysis, the presence of oriented YAG : Nd crystals ranging in size from 25 to 37 nm in the silica glass matrix of fibre is established. Measurements of the spectral dependence of optical losses in fibre show the presence of absorption bands of the optical signal, characteristic of Nd{sup 3+} ions. The shape of the luminescence spectra of nanocrystals is typical of YAG : Nd with a radiation peak at a wavelength of 1064 nm. (paper)