Tunable color-center lasers and their use in the selective spectroscopy of disordered media

The requirements for laser sources suitable for the selective spectroscopy of rare-earth ions are determined, and it is shown that these requirements are best met by lasers using F2, F2(+), and F2(-) color centers in LiF crystals. Implementations of tunable lasers using these color centers are described, with attention given to the problems involved in the development of lasers of this type. Results of the selective spectroscopy of Yb(3+) and Nd(3+) ions, that have been obtained using the color center lasers, are reported.