How to optimize gain in solid-state dielectric media

At the beginning of what some people believe will become the "century of the photon" we are still struggling with the problem that stands at the beginning of the "world of photonics" - the generation of light in an appropriate and efficient way. This presentation focuses on coherent light generation in dielectric crystals and glasses activated by rare-earth and transition-metal ions. It aims at providing an overview of the important aspects of these light sources, such as host materials, their growth and structuring, spectroscopy of the doped ions, population dynamics in lasers, wavelength conversion, geometries of gain medium and resonator, as well as optical power scaling and its undesired consequences, thermal and thermo-optical problems - a "hot" issue in recent years.