Photoluminescence of rare-earth-doped glasses

Rare-earth elements are of interest in several high-tech and environmental application areas, the two major ones concerning magnetic and optical devices. In the latter field, one can exploit the unique photoluminescence properties of rare-earth ions to develop novel or advanced lasers and optical amplifiers. Glasses have been known for a long time as a convenient host for rare earths and have been widely used for the fabrication of solid-state lasers. Recently, guided-wave format has added several advantages, namely the small size, the high pump power density, and the larger flexibility in design and fabrication. Thus, in the last few years, due to the great development of optical communications, an increasing research and development activity has been focused on the design and manufacture of fibre optic and integrated optic lasers and amplifiers, especially of those based on Er3+-doped glasses. The aim of the present paper is to highlight the application of the spectroscopic techniques to the characterization of rare-earth-doped glasses and to present a brief overview of the efforts and progresses made in the area of micro-optic and integrated-optic lasers and amplifiers. A brief summary of the fundamentals of the photoluminescence properties and of the measurements techniques is also provided.