Mesoporous metal oxide semiconductor-clad waveguides

Optical waveguides were prepared by depositing a sol gel-derived titania film 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 critical angle of total internal reflection. Thus, the titania-coated waveguides propagate light in an attenuated total reflection made, despite the relatively high refractive index (n = 1.8 in air) of the titania film relative to 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.