Influence of the preparation conditions of erbium-doped bismuth germanate glasses on its optical response

The influence of the glass preparation conditions (melting temperature and crucible material) and of post-preparation heat treatments on the refractive index, optical absorption and near infrared luminescence of an Erbium-doped BiO-GeO glass has been studied. The optical absorption and emission are strongly dependent on these conditions and Bi to Er energy transfer is observed to occur. In some cases, a high absorption due to the formation of Bi nanoparticles is obtained. Consequently transmission-temperature hysteresis loops during heating-cooling cycles are observed due to the reversible melting and solidification of nanoparticles. Our results indicate that, with adequate composition and preparation conditions, bismuth germanate glasses can be very useful for a large variety of optical devices, such as amplifiers and thermo-optical modulators and filters. © 2016 Elsevier B.V. All rights reserved