Strip-Loaded High-Confinement Waveguides for Photonic Applications

Sol-gel is a promising deposition technique for the fabrication of silica-on-silicon photonic components. Silica-titania compositions provide large index differences, and thus strong mode confinement, and are suitable hosts for Er-doped optical amplifiers. We have developed channel waveguides based on phosphosilicate strip loads over high index titania-doped guiding layers. Here we demonstrate that low propagation loss (0.3 dB/cm) can be obtained in such guides at optical communication wavelengths. Alumina co-doped guiding layers are shown to inhibit OH retention without causing titania segregation, and reduced humidity during spinning is shown to be necessary to achieve low propagation losses.