Preparation and trans-cis isomerization of azobenzene-containing TiO ₂/ormosils hybrid films derived at a low temperature sol-gel process for photonic applications

Azobenzene-containing TiO₂/γ- glycidoxypropyltrimethoxysilane and methyltrimethoxysilane hybrid films are prepared by combining a low temperature sol-gel process and a spin-coating technique. The trans-cis isomerization of azobenzene small molecules inside organic-inorganic hybrid films is induced by a photoirradiation under UV light. It is noted that below a baking temperature of 150 °C is necessary for the hybrid films in optical storage or optical switching applications. The change of the refractive index and thickness of the hybrid films with real-time heating temperature are observed by using a prism coupling technique. The structural properties of the hybrid films are also characterized and investigated by thermal gravimetric analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the as-prepared hybrid films might allow directly integrating the optical storage or optical switching devices with the waveguide devices on the same chip.