Energy transfer process from Tm<sup>3+</sup> ions to Tb<sup>3+</sup> ions was investigated in CsCdBr<sub>3</sub>:Tb,Tm and KPb<sub>2</sub>Cl<sub>5</sub>:Tb,Tm crystals. Energy transfer quantum efficiency were found as high as <i>q<sub>tr</sub> </i>= 68 % for the CsCdBr<sub>3</sub>:Tm(1.0%),Tb(0.5%) crystal and <i>q<sub>tr</sub> </i>= <i>22%</i> for the KPb<sub>2</sub>Cl<sub>5</sub>:Tm(2.5%),Tb(0.2%) crystal. It is shown that they are promising candidates as laser crystals for MIR, suitable for diode laser pumping at 0.8 μm in Tm<sup>3+</sup> absorption band.

© 2003 Optical Society of America

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