Integrated optical amplifiers based on rare-earth doped (red) oxide glasses

Oxide glasses have been used since long time to host a number of active compounds, first of all rare-earth (RE) ions, for lasing. Recently, the advantages offered by guided-wave format, namely the small size, the high pump power density, and the larger flexibility in design and fabrication, led to the development of fiber lasers and amplifiers based on Er3+-doped glasses. Currently, a growing activity is aimed at achieving large optical gain in Er3+-doped planar waveguides, having in mind the single-chip realization of integrated optical amplifiers and lasers. The aim of the present paper is to provide a quick overview of this area and to briefly discuss possible future developments.