Sol-gel derived thin films of LiTaO3 on SiO2/Si substrates for optical waveguide applications

Thin films of lithium tantalate have been derived on SiO2/Si substrate by s ol-gel method. The sol is prepared by mixing LiOC2H5 and Ta(OC2H5)(5). The film is deposited by spin- coated and annealing at 600 degreesC. The film i s characterized by means of X-ray diffraction, atomic force microscopy, and the m-line technique. The experimental results show that the film has crys tallized into the pure trigonal phase and it is microscopically continuous and uniform. The crystalline size ranges from about 33nm to 96nm. The refra ctive index of the from is measured to be 1.84 at the wavelength of 633nm a nd the film is found to support several guiding modes at this wavelength.