Rare-earth converters of the emission spectrum of neodymium lasers

The energy-conversion properties of rare-earth anti-Stokes phosphors (e.g., BaYb2F8:Er, LiYbF4:Tu, LiYbF4:Ho, LaF3:Dy, and BaYb2F8:Dy) are examined. Attention is given to the current status of studies on the extension of the generation frequency range of rare-earth lasers by means of optical pumping using neodymium lasers. Spectral conversion of the pump radiation is achieved through processes that take place in optically excited rare-earth crystals. Such processes as radiative and nonradiative transitions, intercenter transfer of excitation energy, and the interaction of excited states lead to the summation of the energy of electronic excitation. Principles underlying the generation of stimulated emission over the 3-5 micron range using rare-earth crystals are discussed.