A silicon-based technology for the fabrication of smooth optical devices

In this paper, we report a novel fabrication technique for integrated silicon waveguides and devices. Unlike conventional silicon-on-insulator (SOI) technology, this process uses proton beam writing and electrochemical etching in hydrofluoric acid to fabricate strip waveguides directly in silicon, eliminating the need for SOI substrate. We characterized and simulated the propagation loss and surface roughness scattering of these waveguides. A surface smoothening technique based on controlled oxidation has also been used to achieve a root-mean-square roughness of better than 3 nm, pushing the propagation loss down to 1dB/cm.