Homogeneous and nanocomposite rare-earth-activated glasses for photonic devices

Since the discovery of optical fibers, the possibility to develop optically confined structures has opened new possibilities for making novel optical components. Rare earth-activated confined structures thus offer interesting solutions for this end. A growing activity in this field is aimed at the development of optical amplifiers in planar form based on rare-earth-activated glasses to provide devices such as lossless splitters, which can find applications in the metropolitan and local area networks. A further development to enhance the spectroscopic properties is achieved by rare-earth co-activated nanocomposite materials, also in planar format. The aim of this paper is to give a review concerning the advances in glass-based photonic systems, where light confinement or the presence of nanostructured hosts for the rare-earth induces an enhancement and a control of the optical and/or spectroscopic properties.