Mesoporous metal oxide semiconductor-clad waveguides

Optical waveguides were prepared by depositing a sol gel-derived titania fi lm onto a silica substrate. The titania film is mesoporous, with pore sizes ranging from 3 to 8 nm. Deposition of the titania does not change the crit ical angle of total internal reflection. Thus, the titania-coated waveguide s propagate light in an attenuated total reflection made, despite the relat ively high refractive index (n = 1.8 in air) of the titania film relative t o the silica substrate (n = 1.5). The optical and structural properties of these films suggest the possibility of developing efficient photocatalytic reactors or improved optical chemical sensors.