Low-loss silica-based optical film waveguides deposited by helicon-activated reactive evaporation

Planar silica-based optical waveguides have been deposited by a plasma helicon-activated reactive evaporation system, at a low temperature and with reduced hydrogen contamination, on thermally oxidized silicon wafers. The transmission loss of the rib waveguides, formed on the deposited films by etching with hydrofluoric acid, is determined to be lower than 0.1 and 0.7 dB/cm at wavelengths of 1310 and 1510 nm, respectively, for TE polarization. The influence of substrate leakage on propagation loss is determined numerically and compared with experimental results for TE and TM polarizations. The presence of the OH vibrational overtone band in the fabricated waveguides, at a wavelength of around 1385 nm, is discussed in terms of the waveguide structure.