Low-loss rib waveguides containing Si nanocrystals embedded in SiO2

We report on the study and modeling of the structural and optical properties of rib-loaded waveguides working in the $600–900\text{-}\mathrm{nm}$ spectral range. A Si nanocrystal (Si-nc) rich $\mathrm{Si}{\mathrm{O}}_2$ layer with nominal Si excess ranging from 10% to 20% was produced by quadrupole ion implantation of Si into thermal $\mathrm{Si}{\mathrm{O}}_2$ formed on a silicon substrate. Si-ncs were precipitated by annealing at $1100°\mathrm{C}$ , forming a $0.4\text{-}\mu \mathrm{m}$ -thick core layer in the waveguide. The Si content, the Si-nc density and size, the Si-nc emission, and the active layer effective refractive index were determined by dedicated experiments using x-ray photoelectron spectroscopy, Raman spectroscopy, energy-filtered transmission electron microscopy, photoluminescence and $m$ -lines spectroscopy. Rib-loaded waveguides were fabricated by photolithographic and reactive ion etching processes, with patterned rib widths ranging from $1\text{to}8\mu \mathrm{m}$ . Light propagation in the waveguide was observed and losses of $11\mathrm{dB}∕\mathrm{cm}$ at 633 and $780\mathrm{nm}$ were measured, modeled and interpreted.