Investigation of the role of silver on spectroscopic features of Er3+-activated Ag-exchanged silicate and phosphate glasses

We present a spectroscopic investigation on Er/Ag co-doped platelets of silicate and phosphate glasses with the aim of assessing the effect of silver as a sensitizer for erbium. The silver was added by immersing the samples, at 663 K for 67 h, in a molten salt bath of molar concentration 0.5% AgNO3 and 99.5% NaNO3. Additive heat treatments in air at different temperatures, ranging from 673 K to 773 K for 30 min and cooling in air after each anneal, were performed on both the silver-exchanged and the silver-free plates. The optical and spectroscopic features of the samples were investigated by photoluminescence measurements in the region of the I-4(13/2) -> I-4(15/2) transition of the Er3+ ion, excitation spectra in the range from 360 to 750 nm, and absorption measurements. Increases of the Er 31 luminescence at 1.5 mu m are demonstrated when the excitation is in an absorption band, located at 420 nm, possibly originating from the surface plasmon resonance of silver particles. (c) 2005 Elsevier B.V. All rights reserved.