Mid-infrared Luminescence Properties of Tm~(3+) and Ho~(3+) Co-doped Fluorogermanate Glasses
Tm~(3+)和Ho~(3+)双掺氟锗酸盐玻璃的中红外发光性质

Fluorogermanate glasses with the compositions of 65GeO_2-12AlF_3-10BaF_2-8Li_2O-5La_2O_3 codoped with Tm~(3+) and Ho~(3+) ions are fabricated by conventional melting method.According to the Judd-Ofelt theory,the J-O strength parameters(Ω_2,Ω_4,Ω_6)of Ho~(3+) 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 ~3H_6→~3F_4 transition of Tm~(3+) and the ~5I_8→~5I_7 transition of Ho~(3+)(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 Tm~(3+) and infrared emission spectra of Tm~(3+) sensitized Ho~(3+) ions are studied.The results indicate that the energy transfer efficiency of Tm~(3+)(3F_4)→Ho~(3+)(5I_7)ions is enhanced and the infrared fluorescence intensity at ～2.0 μm is increased as the Ho~(3+) co-doped into glass.