Up-conversion and excitation energy transfer between impurity ions in Pr{sup 3+} : Y{sub 2}SiO{sub 5}, Pr{sup 3+} : Lu{sub 2}SiO{sub 5}, and Pr{sup 3+} : Gd{sub 2}SiO{sub 5} crystals

Anti-Stokes fluorescence from the {sup 3}P{sub 0} level of impurity ions was detected in Pr{sup 3+} : Y{sub 2}SiO{sub 5}, Pr{sup 3+} : Lu{sub 2}SiO{sub 5}, and Pr{sup 3+} : Gd{sub 2}SiO{sub 5} crystals non-resonantly pumped by laser radiation with a certain power density. The integrated intensity of the anti-Stokes fluorescence depends nonlinearly on the pump power density. As the atomic concentration of impurity ions was increased from 0.3% to 0.6% and 1.8%, the anti-Stokes fluorescence intensity was saturated due to the concentration quenching of the {sup 1}D{sub 2} term of the impurity Pr{sup 3+} ions. The anti-Stokes fluorescence and quenching of the {sup 1}D{sub 2} term occur due to the cross relaxation of the electronic energy of excited terms of the Pr{sup 3+} ions. (lasers, active media)