%0 Book Section %T Concentration and power dependences of level population of 2.8-mu m laser transition in YLF : Er crystals under CW laser diode pumping publisher Spie-Int Soc Optical Engineering %D 2001 %U 0-8194-4040-X %@ https://hdl.handle.net/20.500.14352/61008 %X An influence of interionic cross relaxation processes (upconversion, selfquenching) on concentration and power dependences of the inverse population of ^4I_(11/2) and ^4I_(13/2) laser levels in YLF:Er crystals under CW laser-diode pumping were studied both theoretically and experimentally. Computer simulations were carried out taking into account not only pair interaction but also the multi-ion interaction in the whole system. Optimal Er concentration for 3 - µm CW lasing was estimated as 10 - 15%. %~