The re- sults show thatthe cross relaxation rate at LD pumping depends on the doped Tm3 + concentration and has a quite speed for used samples,which will induce a rather large population of 3 F4 manifold,the energy transfer rate fro.

8 μm emission and the cross-relaxation mechanism are discussed.

0 μm is generated through two processes:the cross-relaxation between Tm3+,and the holmium particles population to 5I7 via the energy transfers from Tm3+ to Ho3+.

8 μm emission with the pump power prove that the particle number in 3F4 comes from the cross-relaxation process of 3H4+3H6→23F4.

Theoretic estimation of lasing threshold of a three-level systsm containing cross relaxation;

Results of meausred radioluminescence spectra show that energy transfer mechanisms occurring from Gd~(3+) cations towards Tb~(3+) emssion centers as well as the cross relaxation among Tb~(3+) cations within the certain concentration range exert tremendous effects on the emission intensity of glasses.

Its found that the energy match between rare earth ions is realized easily by the phonon joining at room temperature,which result to cross relaxation strengthen and the lifetime of 664 nm radiation be longer.