Mid-infrared luminescence and energy transfer of Tm3+ in silicate glasses by codoping with Yb3+ ions

A kind of novel silicate glasses doped with Tm3+ sensitized by Yb3+ were prepared by conventional melt quenching method. The optical properties of the synthesized glasses were theoretically and experimentally investigated. Based on the absorption spectra and the Judd-Ofelt theory, the J-O intensity parameters (Ωt), radiative transition probability (400.4 s−1), fluorescence lifetime (4.99 ms) and absorption and emission cross sections (σe = 2.51 × 10−20 cm2) were calculated. According to fluorescence spectra, the 1.8 μm emission of Tm3+ could be greatly enhanced by adding proper amount of Yb3+ under the excitation of 980 nm and the optimized concentration ratio of Tm3+ and Yb3+ was found to be 1:3 in the present silicate glass system. Besides, the energy transfer mechanism between Yb3+ and Tm3+ were thoroughly discussed. With the assistance of Yb3+, the lifetime of Tm3+ from 0.54 ms increased to 1.42 ms. The energy transfer efficiency from Yb3+ to Tm3+ could reach 90.94%, and the energy transfer coefficient was 5.43 × 10−41 cm6/s. The content of OH− was measured. The above results showed that Tm3+/Yb3+ co-doping could be expected to a promising way to achieve high efficient 2 μm lasing pumped by a 980 nm LD.