Patent ID: 7123805

Claim:
A method of reducing waveguide roughness comprising: oxidizing the surface of a waveguide to form an oxidized layer, said oxidation is governed by the rate of reactant to the surface of said waveguide to define a reaction-limited regime once said oxidized layer grows and oxygen diffuses through said surface of said waveguide to define a diffusion-limited regime at an elevated temperature of at least 1050 C.; and isotropically etching the oxidized layer every time said reaction-limited regime is approaching said diffusion-limited regime; the oxidized layer is repeatedly oxidized and etched so that said waveguide is continuously oxidized in the reaction-limited regime isotropically etching comprises anhydrous HF, reducing the overall time of oxidation and volume of oxidized material so that said waveguide has its sidewall roughness reduced efficiently enabling high transmission rates of guided light.