The spectroscopic and laser kinetic properties of the trivalent ytterbium i
on in various solid-state media are reviewed. Contrasts between four- and q
uasi-three-level lasers (e.g,, Nd:YAG versus Yb:YAG) are highlighted. Vario
us architectures suitable for use in high-brightness high-power Yb :YAG las
ers are examined, and achieved laser performance levels are summarized. The
properties of alternative ytterbium-doped laser gain media are reviewed, a
nd early laser results are cited.