Ultrafast laser plasma doping of Er³⁺ ions in silica-on-silicon for optical waveguiding applications.

An ultrafast laser plasma doping (ULPD) technique is used for high concentration doping of erbium ions into silica-on-silicon substrate. The method uses a femtosecond laser to ablate material from TeO₂-ZnO-Na₂O-Er₂O₃ (Er-TZN) target glass. The laser-generated plasma modifies the silica network, producing a high-index-contrast optical layer suited to the production of on-chip integrated optical circuits. Cross-sectional analysis using scanning electron microscope with energy dispersive x-ray spectroscopy revealed homogeneous intermixing of the host silica with Er-TZN, which is unique to ULPD. The highly doped layer exhibits spectroscopic characteristics of erbium with photoluminescence lifetimes from 10.79 to 14.07 ms.