Optical and surface properties of inorganic and hybrid organic-inorganic silica-titania sol-gel planar waveguides

Inorganic and hybrid organic-inorganic silica (SiO2)-titania (TiO2) planar waveguides, with a relative molar composition 70-30, have been fabricated b y sol-gel dip-coating. The composition and the density of the film samples have been measured by Rutherford backscattering spectrometry, nuclear react ion analysis and elastic recoil detection analysis. The measured compositio ns have been found to agree with the nominal composition of the sols. The f ilm density of the inorganic samples increased with the firing temperature in the range 1.80-2.58, A root mean square roughness (rms) <1 nn was measur ed on the surface of the samples by atomic force microscopy. A refractive i ndex in the range 1.61-1.54 was measured (lambda = 632.8 nm). The inorganic waveguides had smaller losses (similar to 0.3 dB cm(-1)) compared to the h ybrid waveguides (similar to 1 dB cm(-1)). (C) 1999 Elsevier Science B.V. A ll rights reserved.