Preparation and characterization of ZnO particles embedded in organic-inorganic planar waveguide by sol-gel route

Hybrid organic-inorganic waveguides based on ZnO-(3-glycidoxypropil) trimethoxisilane (GPTS) have been fabricated by sol-gel route. A transparent sol of ZnO was added to the GPTS host and the resulting sol was deposited on silica substrates by spin coating technique. Waveguides with different molar composition (100-x)GPTS-xZnO (x=10, 20, 30) were investigated by different diagnostic techniques. Morphological measurements were carried out by means of an AFM apparatus, and a roughness of few nanometers was determinate for all the waveguides. Optical properties such as refractive index, thickness, number of propagating modes and attenuation coefficient were measured at 632.8, 543.5, 1319 and 1542 nm by the prism coupling technique as a function of the ZnO content. Photoluminescence measurements showed a large luminescence band in the region between 350 nm to 600 nm with a main peak centred at about 380 nm, due to the presence of ZnO nanoparticles.