AbstractA plasma assisted CVD technique for fabrication of optical planar waveguides on silica substrates is described. Silica films doped with germania have been deposited at 1000-1100°C with<0.3 dB cm-1attenuation, sharp refractive index profiles, and satisfactory adhesion and integrity. Deposition has been achieved at temperatures down to 100°C, but resultant film attenuation, adhesion, and integrity are substantially inferior. Codeposition of fluorine is shown to improve the mechanical properties, while cladding and buffer layers are expected to enhance the optical performance of the waveguides.