Flame hydrolysis deposition of photosensitive silicate layers suitable for the definition of waveguiding structures through direct ultraviolet writing
This thesis presents the construction of equipment suitable for the fabrication of doped silicate layers thxough use of the Flame Hydrolysis Deposition technique. The subsequent optimisation of equipment and deposition processes has seen the realisation of fully dense amorphous silica layers doped with Phosphorus, Boron and Germanium. Accurate control of dopant inclusion has allowed the independent control of processing properties and optical characteristics, while maintaining the tolerances imposed by waveguiding. The Flame Hydrolysis Deposition Technique has been applied to the fabrication of three layer nominally index matched pianar waveguiding structures, consisting of low photosensitivity cladding layers and high photosensitivity core layers. Application of the direct UV writing technique to planar structures has been investigated, and the induced physical and optical effects characterised. The additional application of the Deuterium loading process has been used to further enhance photosensitivity and has resulted in the production of channel waveguides with propagation losses of ~0.2dB/cm and relative core refractive indices of the order 1x10.