Fluorogermanate glasses with the compositions of 65GeO2-12AlF3-10BaF2-8Li2O-5La2O3 codoped with Tm3+ and Ho3+ ions are fabricated by conventional melting method.According to the Judd-Ofelt theory,the J-O strength parameters(Ω2，Ω4，Ω6)of Ho3+ are calculated,by which the radiative transition probabilities,fluorescence branching ratios and radiative lifetimes are obtained.According to McCumber theory,the absorption and emission cross-sections corresponding to the 3H6→3F4 transition of Tm3+ and the 5I8→5I7 transition of Ho3+(at 2.0 μm)are obtained,and respective gain cross section spectra are computed as a function of population inversion.With 808 nm LD excitation,the cross-relaxation process of Tm3+ and infrared emission spectra of Tm3+ sensitized Ho3+ ions are studied.The results indicate that the energy transfer efficiency of Tm3+(3F4)→Ho3+(5I7)ions is enhanced and the infrared fluorescence intensity at ~2.0 μm is increased as the Ho3+ co-doped into glass.