Nanocomposite photonic glasses and confined structures optimizing Er3+ - luminescent properties

The recent developments of optically confined structures and nanocomposite materials activated by rare earth ions have opened new possibilities in the field of both basic and applied physics, in a large area covering Information Communication Technologies, Health and Biology, Structural Engineering, and Environment Monitoring Systems. As far as optical telecommunications are concerned, Er3+-activated glasses have become one of the key materials because of their relevance for the development of optical amplifiers. The short-term goal is to develop appropriate material systems and devices to exploit at the best the luminescence properties of Erbium. Er3+-activated confined structures at different scales thus offer interesting solutions. The last decade has seen a remarkable increase in the experimental efforts to control and enhance emission properties of emitters by tailoring the dielectric surrounding of the source. With this aim, several approaches, using nanocomposite materials and/or specific geometries, such as planar interfaces, photonic crystals, solid state planar microcavities, dielectric nanospheres, and spherical microresonators , have been proposed. Nanostructured materials have been attracting a very large interest in both academic and industrial communities over the past decade, due to the remarkable variations in fundamental electrical, optical and magnetic properties that occur as one moves from a bulk "homogeneous" material to a particle or a cluster of dimensions in the 1 to 100 nm range. Moreover, the possibility of developing optical confined structures has opened new possibilities for novel optical components, and the glass-based planar technology appears to be consolidated enough to allow the design of complex optical devices. A more effective control of luminescence properties may be achieved by rare earth-activated microcavities, which represent a particular class of photonic crystals. The aim of this paper is to give an overview of the advances in glass-based photonic systems, where light confinement or presence of nanostructured hosts induces an enhancement of optical and/or spectroscopic properties of the rare earth ion(s). In particular, the following topics will be highlighted: (i) planar optical waveguides, that, together with optical fibers, represent the most popular guided-wave structure; (ii) rare earth-activated glass ceramics planar waveguides, where the active ions are embedded in the crystalline phase, combining the mechanical and optical properties of the glass with a crystal-like environment for the rare-earth ions; (iii) Er3+-activated Ag-exchanged silicate glass, where the role of silver as erbium sensitizer is investigated; (iv) dielectric 1-D photonic band gap structures or planar microcavities, where the rare-earth luminescence is enhanced and selected in frequency.