Design and fabrication of SiO2/Si3N4 CVD optical waveguides

In this paper the design and fabrication of silicon-based optical waveguides are revisited. The goal was to develop a novel deposition process to minimize leakage losses, by allowing the deposition of a thick SiO₂ lower cladding as an optical buffer layer. Indeed, comparison between theory and experimental data suggests that for the fabricated waveguides the dominant loss mechanism is scattering caused by side-walls surface roughness. Optical characterization yielded losses in the same range of state-of-art devices reported in the literature