The optical properties of the rare elements Tm 3+, Ho 3+ and Yb 3+ were systematically investigated in various glasses. The Tm 3 + doped aluminozircofluoride glass shows higher quantum efficiency, longer lifetime and stronger fluorescence intensity than Tm 3 Γ· doped YSGG crystal and other Tm 3 Γ· doped glasses for the 3H4 ~ 3H 6 transition. Similar quantum efficiency, longer lifetime and stronger fluorescence intensity were also found in HO 3 + doped aluminozircofluoride glass for the 5I 7 ~ 5[ 8 transition. The higher quantum efficiencies of Tm 3 + and Ho 3 + in aluminozircofluoride glass are due to the longer lifetime and the lower phonon energy. The fluorescence mechanisms and energy transfer in the Yb 3 +-Tm 3 Γ· system, Yb 3 +-HO 3 + system and Yb 3 +-Tm3+-Ho3+ system were studied. The very strong fluorescence intensities in the yb3+-Tm 3+ system for Tm 3+ and the Yb 3+-Tm3Γ·-Ho 3Γ· system for Ho 3+ which are 1.68 times that of Tm 3Γ· doped YSGG crystal and 2.25 times that of Tm3+-Ho 3Γ· codoped YSGG crystal are attributed to the efficient Yb 3 + -* Tm 3 +, Yb 3 + ~ Ho 3 + and Tm 3 Γ· ~ Ho 3 + energy transfer processes. The fluorescence processes are described by cross relaxations of 2F5/2 ~ 3H 5 ~ 3H 4 "-* 3H 6 ~ 2F7/2 and 2F5/2 ~ 3H 5 (or 2Fs/2