Mesostructured thin films as responsive optical coatings of photonic crystals

A synthetic route is presented to attain high-optical-quality multilayered structures that result from coupling ordered mesoporous titanium oxide thin films to the surface of a dense one-dimensional photonic crystal. Such architectures present spectrally well-defined photon resonant modes localized in the outer coating that finely respond to physicochemically induced modifications of its pore volume. The potential of these porous coatings in detection of environmental changes through variations of the photonic response of the ensemble is demonstrated by performing isothermal optical reflectance measurements under controlled vapor-pressure conditions.