Rare earth-activated nano-composites glass systems for photonics

The scientific and technological activity involving the development of materials at nano-micro scale and related converging technologies allows progress in the conception, design, and realisation of systems and devices with substantially improved performance and significant scientific results. The specific properties of the sol-gel technique make this approach very effective to succeed in the above mentioned topics, with special regard to the development of advanced materials for photonic applications. Some examples will be discussed at the conference, starting with the analysis of different colloidal systems. Silica and polystyrene spheres are presented, as well as core-shell spheres activated by rare earth ions. Starting from the nano spheres, 3D photonic crystals can be fabricated. Some examples of opals are given and it is demonstrated that it is possible to tune the position of the stop band infiltrating the voids of the opal structures with suitable materials. Other examples are presented referring to the case of planar waveguides; here, relevant results have been obtained for rare-earth-activated amorphous and nanostructured SiO2-HfO2 and nanostructured SiO2-SnO2 systems. Of particular interest appears the demonstration of the role of SnO2 nanocrystals as rare earth sensitizers and the possibility to develop suitable fabrication protocols allowing the fabrication of rare earth activated glass ceramic waveguides.