In present work the effect of two different source of silicon Tetraethylorthosilicate and Octamethylcyclotetrasiloxane on
TiO<sub>2</sub>-doped SiO<sub>2</sub> films have been studied. The study reveals that film properties depend on the precursors used for
deposition. The deposited films are crystalline with broad peak between 2θ = 20° - 30° corresponding to SiO<sub>2</sub> and two
strong peak appearing at 2θ = 38.3° and 2θ = 44.6° due to the (004) anatase phase and (210) rutile phase of TiO<sub>2</sub>. It is
also clear from the SEM study that the particle size of films deposited using TEOS are smaller than the one deposited by
The principle of operation and the design techniques for various types of the optical demultiplexers are reviewed. The results for two-channel optical demultiplexer based on optical directional coupler configuration are presented. The device for separating two wavelengths with 4 nm spacing is designed on the Silicon substrate in SiO<sub>2</sub>/SiO<sub>2</sub>-TiO<sub>2</sub>/SiO<sub>2</sub> rib waveguide. The rib waveguide design techniques using the effective index method are described. The propagation of the two wavelengths through the device is calculated using the computer tools based on the beam propagation method (bpm). The dependence of the device length required for separation of the two wavelengths on the rib waveguide parameters is studied. The waveguide rib width and separation between the parallel waveguides are the parameters those affect the value of the length required for separating the two wavelengths to a greater extent. The guide thickness inside the rib also has considerable effect on the device length. The clad thickness and rib height, however, were found to be the least affecting parameters. The optimization techniques for the rib waveguide and the coupler parameters for achieving the demultiplexing with the minimum length of the device are explained. The proposed fabrication techniques for the SiO<sub>2</sub>/SiO<sub>2</sub>-TiO<sub>2</sub>/SiO<sub>2</sub> rib waveguide are presented.