On optical activity of Er³⁺ ions in Si-rich SiO₂ waveguides

Photoluminescence spectroscopy was used to explore the optical activity of Er3+ ions in Si-rich Si O2 waveguides prepared by ion implantation. Measurements were performed for a series of materials characterized by different Si excess levels, Er concentrations, and annealing temperatures. The highest fraction of optically active Er3+ ions which can be efficiently activated by nonresonant pumping was found to be 2.6%. This was realized in a waveguide with an Er concentration of [Er] = 1018 cm-3 and Si excess of 20%, annealed at 900 °C. This optical activity level is insufficient to realize optical gain. It is therefore clear that further material improvement is needed before optical amplification in Si O2: Er matrices sensitized by Si nanocrystals/nanoclusters can be achieved.