Spectroscopic properties of Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glasses containing silver nanoparticles

Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glasses containing silver nanoparticles (NPs) are prepared using the conventional melt-quenching technique. Detailed structure and optical characterizations have been carried out. The observed localized surface plasmon resonance (SPR) band is evidenced to be around 440 nm. Four frequency up-conversion (UC) emission bands blue (476 nm), green (524 and 546 nm) and red (658 nm) corresponding to 1G4→3H6 (Tm3+), (2H11/2, 4S3/2) →4I15/2 (Er3+) and 4F9/2→4I15/2 (Er3+) transitions, respectively, were simultaneously observed under 980 nm excitation at room temperature. It is confirmed that the anneal duration plays an important role in increasing the UC luminescence intension, however, further increase in the annealing time reduces the intensity. The enhancement in UC emission intensity is mainly attributed to the large local electric field induced by the silver NPs. The quenching in the luminescence intensity is due to the energy transfer from Tm3+, Er3+ and Yb3+ ions to silver NPs. Furthermore, the results suggest that the embedded silver NPs may adjust the UC luminescence color in the studied emission system.