Decades of scientific research on spectroscopic properties of f-shell electrons has
spawned an extensive array of applications for rare-earth activated luminescent
and laser materials. From phosphors activated by Eu^^ , Eu^^ and Tb^^ ions for
lighting and display to crystals and glasses doped with Er^^ and Yb^* for
infirared-to-visible up-conversion, rare-earths represent a large share of the
lighting materials market. Currently, Nd^^ doped crystals such as Nd^"^: YAG
(Y3AI5O12) and Nd^^ : YVO4 are the dominant laser media for high power and
compact solid-state lasers, while Er^^ doped phosphate and siUcate glasses
prevalent in optical fiber amplifiers and microlasers used in optical
teleconmiunications. Thanks also to materials science development, rare-earths
will receive even wider use in the future, entering in the new world of
nanotechnologies for instance. In addition to rare-earth activated phosphors and
solid-state lasers, optical applications of rare-earths are already an integral part of
internet and data conununications and are expected to be applied to information
storage and processing, and organic and biological devices.